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1. Peak to peak value of a sine wave is
a- Twice the maximum or phase value of sine wave
b- Half of the maximum or phase value of sine wave
c- Four times the maximum or phase value of sine waved
d- Equal to the maximum or phase value of sine wave
Answer :
2. According to the coulomb’s law, the force between two point charges is
a- Directly proportional to the product of the charges
b- All of these
c- Along the line joining them
d- Inversely proportional to the square of the distance between them
Answer :
3. The most common waveforms of ac is
a- Saw tooth
b- Square
c- Triangular
d- Sinusoidal
Answer :
4. The most effective earth plate is
a- Cast - iron plates
b- Galvanized iron plates
c- Copper plates
d- All of these
Answer :
5. Which among the following is true about ohm’s law?
a- V = IR
b- All of these
c- I ∝ V
d- I = V/R
Answer :
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6. an electron charge is equal to
a- – 1.6019 x 10^–19C
b- – 1.925 x 10^–31C
c- 1.925 x 10^–31C
d- 1.6019 x 10^-19C
Answer :
7. he number of instantaneous values between zero and the peak value is
a- Infinity
b- Eleven
c- One
d- Zero
Answer :
8. The equation for electric flux density is given by
a- D = ε/V
b- D = ε/E
c- D = εV
d- D = εE
Answer :
9. In Fleming’s right hand rule, the direction of the induced emf in the conductor is given by
a. Index figure
b. Middle figure
c. Thumbd.
d.None of these
Answer :
10. When windings of 3 - phase induction motor is rotated in a magnetic field, then the emf induced in each phase are of
a- Different magnitude and different frequency
b- Same magnitude but different frequency
c- Different magnitude but same frequency
d- Same magnitude and same frequency
Answer :
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11. The materials with permeability less than unity are called
a- Ferromagnetic materials
b- Anti ferromagnetic materials
c- Paramagnetic materials
d- Diamagnetic materials
Answer :
12. Yoke in a dc machine serves the function of
a- All of these
b- Offers a path of low reluctances to the magnetic flux produced by the poles
c- Protects the dc machine from harmful atmospheric elements like dust, moisture and gases
d- Providing mechanical support to the poles
Answer :
13. For a two - way position control of lamp, the number of switches required is
a- Four
b- One
c- Two
d- Three
Answer :
14. The two alternating quantities could be added by constructing
a- Squares
b- Parallelograms
c- Trapeziums
d- Rhombus
Answer :
15. In a 3 - phase star connected balanced induction motor, the line voltage is equal to the
a- √3 times the phase voltage
b- 1/√3 times the phase voltage
c- 3 times the phase voltage
d- 1/3 times the phase voltage
Answer :
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16. Permanent magnet are manufactured by
a- Iron and cobalt
b- Copper sulphate
c- ALNICO
d- Cobalt and nickel
Answer :
17. A radian is defined as the central angle, for which length of its arc
a- Should be less than radius
b- None of these
c- Should be equal to the radius
d- Should be greater than radius
Answer :
18. Necessity of earthing is to
a- Protect the human being from shock
b- Protect tall building
c- All of these
d- Maintain the line voltage
Answer :
19. Wattmeter is a / an
a- Recording instrument
b- Indicating instrument
c- All of these
d- . Integrating instrument
Answer :
20. The undue deterioration in wiring due to the action of dampness, fumes, weather etc is
a- Appearance
b- Earthing
c- Permanence
d- Mechanical immunity
Answer :
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21. Electrical appliances which works on the electromagnetic principle is / are
a- All of these
b- Generators
c- Transformers
d- Motors
Answer :
22. The amplitude or peak value or maximum value of an alternating voltage is given by the coefficient of the
a- Cotangent of the time angle
b- Tangent of the time angle
c- Sine of the time angle
d- Cosine of the time angle
Answer :
23. The voltage of the earthed appliance when it is higher and when it is lower than the earth potential will
a- Increase to zero, increase to zero
b- Increase to zero, fall to zeroIncrease to zero, fall to zero
c- Fall to zero, fall to zero
d- Fall to zero, increase to zero
Answer :
24. Commutator motors have
a- None of these
b- Approximately uniform torque
c- Non - uniform torque
d- Absolutely uniform torque
Answer :
25. In a star connected system, the current flowing through the line is
a- Equal to the phase current
b- Lesser than the phase current
c- None of these
d- Greater than the phase current
Answer :
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26 The magnetic materials which are strongly attracted by the magnet is
a-Ferromagnetic materials
b-Diamagnetic materials
d-Anti ferromagnetic materials
a-Paramagnetic materials
Answer :
27. The terminal voltage in the separately excited generators is given by
a- V = Eg + Ia Ra - If Ra
b- V = Eg - Ia Ra - If Ra
c- V = Eg – Ia Ra
d- V = Eg + Ia Ra
Answer :
28. One coulomb of charge is equal to the charge of
a- 1.625 x 10^–31 electrons
b- 1.095 x 10 ^–19 electrons
c- 6.242 x 10^18 electrons
d- 6.025 x 10^–19 electrons
Answer :
29. Electric field intensity is
a- Directly proportional to the force applied
b- Inversely proportional to the charge
c- Inversely proportional to the force applied
d- Directly proportional to the permittivity
Answer :
30. Three - phase induction motor is more suitable than single - phase because
a- Better power factor compared to single - phase
b- It is self starting
c- All of these
d- Better efficiency compared to single - phase
Answer :
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31. The springs should be
a- . All of these
b- Free from mechanical stress
c- Sufficient cross-sectional area
d- They should have a small resistance
Answer :
32. In gravity control, at the zero position of the pointer the controlling torque is
a- Zero
b- 0.5
c- 7
d- One
Answer :
33. In a self excited generator, if the series field opposes the shunt field, then the generator is
a- Differentially compounded
b- None of these
c- Cumulatively compounded
d- Series generator
Answer :
34. Root mean square value of current is equal to
a- 0.707 times the maximum value
b- 1.414 times the maximum value
c- 1.732 times the maximum value
d- Twice the maximum value
Answer :
35. If the voltage increases from zero to peak value and decreases back to zero during one alteration, then the average value must be
a- Less than zero
b- Greater than peak value
c- None of these
d- Between zero to peak value
Answer :
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36. The ratio of maximum value to effective value of an alternating quantity is called
a- . Crest factor
b- All of these
c- Peak factor
d- Amplitude factor
Answer :
37. In half wave rectifiers, diode conducts during
a- Only negative half cycle
b- Only positive half cycle
c- Both positive and negative half cycle
d- Neither in positive half cycle nor in negative half cycle
Answer :
38. Reluctance in a magnetic material is a property by virtue of which it opposes the creation of
a- Electric lines of force
b- Magnetic flux
c- Electric flux
d- Electric field density
Answer :
39. The magnetic effect is used in
a- Moving iron attraction type instrument
b- Electrostatic ammeters and voltmeters
c- Moving iron repulsion type instrument
d- All of these
Answer :
40. In any network of wires carrying currents, the algebraic sum of all currents meeting at a point is equal to
a- Sum of all the currents
b- Zero
c- Sum of outgoing current
d- Sum of incoming current
Answer :
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41. Electric pressure is also called
c) voltage
b) power
a) resistance
d) energy
Answer :
42. Out of the following which is an insulating material ?
a-Paper
b-Gold
c-Copper
d-Silver
Answer :
43.Conductance is reciprocal of
(a) resistance
(d) capacitance
(b) inductance
(c) reluctance
Answer :
44. With rise in temperature the resistance of semi-conductors
d) remains constant
a) decreases
b) increases
c) first increases and then decreases
Answer :
45. Out of the following which is not a poor conductor ?
d) Tungsten
b) Copper
a) Cast iron
c) Carbon
Answer :
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46.The resistance of a conductor varies inversely as
c) temperature
d) resistivity
a) length
b) area of cross-section
Answer :
47.The substances which have a large number of free electrons and offer a low resistance are called a) insulators
d) conductors
b) inductors
c) semi-conductors
Answer :
48.The property of a conductor due to which it passes current is called
(d) inductance
(b) reluctance
(c) conductance
(a) resistance
Answer :
49.The S.I. unit of power is
a) Henry
b) coulomb
c) watt
d) watt-hour
Answer :
50.The resistance of a copper wire 200 m long is 21 Q. If its thickness (diameter) is 0.44 mm, its specific resistance is around (c) 1.6 x 10""8 Q-m
(d) 1.8 x 10"8 Q-m
(b) 1.4 x 10~8 Q-m
(a) 1.2 x 10~8 Q-m
Answer :
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51.With rise in temperature the resistance of pure metals
c) first increases and then decreases
a) increases
b) decreases
d) remains constant
Answer :
52.The hot resistance of the bulb’s filament is higher than
its cold resistance because the temperature co-efficient of
the filament is
a) zero
c) positive
d) positive
b) negative
Answer :
53.When resistance element of a heater fuses and then
we reconnect it after removing a portion of it, the power
of the heater will
c) remain constant
d) none of the above
b) increase
a) decrease
Answer :
54.A field of force can exist only between
a) two molecules
d) two metal particles
c) two atoms
b) two ions
Answer :
55.Heat in a conductor is produced on the passage of
electric current due to
c) impedance
a) reactance
b) capacitance
d) resistance
Answer :
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56.A substance whose molecules consist of dissimilar
atoms is called
d) insulator
b) super-conductoR
a) semi-conductor
c) compound
Answer :
57.When electric current passes through a metallic
conductor, its temperature rises. This is due to
a) collisions between conduction electrons and atoms
d) mutual collisions between conducting electrons
c) mutual collisions between metal atoms
b) the release of conduction electrons from parent atoms
Answer :
58.International ohm is defined in terms of the
resistance of
c) a cube of copper
a) a column of mercury
b) a cube of carbon
d) the unit length of wire
Answer :
59.The insulation on a current carrying conductor is
provided
c) both of above factors
d) none of above factors
b) to prevent shock
a) to prevent leakage of current
Answer :
60.Resistance of a material always decreases if
d) none of the above is correct
c) number of free electrons available become more
B) temperature of material is increased
a) temperature of material is decreased
Answer :
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61.A glass rod when rubbed with silk cloth is charged
because
a) it takes in `proton
d) it gives away positive charge
b) its atoms are removed
c) it gives away electrons
Answer :
62.Which method can be used for absolute measurement
of resistances
d) Wheatstone bridge method
b) Releigh method
a) Lorentz method
c) Ohm’s law method
Answer :
63.Ohm's law is not applicable to
a) vacuum tubes
d) circuits with low current densities
b) carbon resistors
c) high voltage circuits
Answer :
64.Which of the following materials has the least
resistivity ?
d) Copper
a) Zinc
c) Mercury
b) Lead
Answer :
65.Two bulbs of 500 W and 200 W rated at 250 V will
have resistance ratio as
d) 5 : 2
b) 25 : 4
a) 4 : 25
c) 2 : 5
Answer :
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66.Which one of the following does not have negative temperature co-efficient ?
a) Aluminium
b) Paper
c) Rubber
d) Mica
Answer :
67.Varistors are
a- non-linear resistors
b- insulators
c- resistors with zero temperature coefficient
d- carbon resistors
Answer :
68.A glass rod when rubbed with silk cloth is charged
because
d) it gives away positive charged) it gives away positive charge
b) its atoms are removed
a) it takes in proton
c) it gives away electrons
Answer :
69.The rating of a fuse wire is always expressed in
a- kWh
b- ampere-volts
c- amperes
d- ampere-hours
Answer :
70.For which of the following 'ampere second' could be the unit
a) Reluctance
d) Energy
b) Charge
c) Power
Answer :
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71.If the efficiency of a machine is to be high, what
should be low ?
d) Ratio of output to input
a) Input power
b) Losses
c) True component of power
Answer :
72.A 2 ohms resistor having 1 ampere current will dissipate the power of
a) 2 Watts
b) 2 Joules
c) 1 Watt
d) 1 Joule
Answer :
73.When 2 volts e.m.f. is applied across a 1 farad capacitor, it will store the energy of
a) 2 Joules
b) 2 Watts
c) 4 Joules
d) 1 Watt
Answer :
74.Thevenin’s equivalent circuit can be used to calculate the power loss in the original circuit
a) True
b) False
Answer :
75.A 1 H inductance carrying the current of amperes will store the energy of
a) 2 Watts
b) 2 Joules
c) 4 Watts
d) 4 Joules
Answer :
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76.If two winding having self-inductances L1 and L2, and a mutual inductance m are connected in series will opposite, then the total inductance of series combination will be
a) L1 + L2 - 2M
b) L1 + L2 + 2M
c) L1 - L2 + 2M
d) L1 + L2 – M
Answer :
77.The parallel circuit resonance magnifies
a) Current
b) Voltage
c) Power
d) None of the above
Answer :
78.What will be the equivalent capacitance (in mF) of three capacitors connected in a series having the capacitance of 0.04 mF, 0.08 mF, and 0.02 mF respectively?
1. 0.026
2. 0.032
3. 0.065
4. 0.011
Answer :
79. Determine the resistance (in ohms) of a 14 m long circular wire when the diameter and the conductivity of the wire are 0.6 m and 12 mho/meter respectively.
1. 1.79
2. 2.84
3. 3.64
4. 4.17
Answer :
80.What will be the color-coding of a resistor when the resistance of the resistor is 50 + 2% ohms?
1. Green-Black-Brown-Red
2. Green-Black-Black-Brown
3. Yellow-Brown-Black-Red
4. Green-Black-Black-Red
Answer :
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81.How much energy is stored in a 100 mH inductance when a current of 1A is flowing through it?
1. 5.0 J
2. 0.05
3. 0.5 J
4. 0.005 J
Answer :
Explanation
The energy stored in the magnetic field of an inductor can be expressed as
E = 1/2 L I2
where
E = energy stored (joules, J)
L = inductance (henrys, H)
I = current (amps, A)
1/2(100 x 10-3 x 1)
50 x 10-3 J
0.05 J
82.In a pure inductive circuit if the supply frequency is reduced to half the current will?
1. Be four times as high
2. Be doubled
3. Be reduced to half
4. Be reduced to one fourth
Answer :
Explanation
The amplitude of the current in a pure inductive circuit is given by
Im = Vm/ωl
And ω = 2πf
Im = Vm/2πfl
Im ∝ 1/f
Hence, when the frequency is halved, the amplitude of the current is doubled in a pure inductive circuit.
83.A 10 pole 25 Hz alternator is directly coupled to and is driven by 60 Hz synchronous motor then the number of poles in a synchronous motor is?
1. 24 poles
2. 48 poles
3. 12 Poles
4. None of the above
Answer :
Explanation
Number of poles of alternator Pa = 10
F = 25 Hz (alternator)
F = 60 Hz (motor)
Then the number of poles of motor Pm =?
Since synchronous motor is directly coupled hence
Synchronous speed of an alternator = Synchronous speed of the motor
(120 x 25)/10 = (120 x 60)/ Pm
Pm = 24
84. For painful shock what is the range of electric shock current at 50 Hertz?
1. 0-1 mA
2. 3-5 mA
3. 0-3 mA
4. 5- 10 mA
Answer :
Explanation
• The damage caused by electric shock depends on the current flowing through the body — 1 mA can be felt; 5 mA is painful.
• Above 15 mA, a person loses muscle control, and 70 mA can be fatal.”
• The amount of damage done by the electric shock depends not only on the magnitude of the current, but it also on which portions of the body that the electric current is flowing through. The reason for this is that different parts of the body have different resistances, which can lead to an increase in current
85.If the power factor is high, then the consumer maximum demands
1. Increase
2. Decrease
3. Becomes zero
4. Remains Constant
Answer :
Explanation
Kva=kw/cos$
Now considering the above equation, for a given requirement of kW, the value of kVA reduces if we have good power factor.
Let us understand with an example,
Consider a case wherein we need 100 kW as output. Now
Case1: for a power factor of 0.8
We would require 120kva for fulfilling the required demand. (Calculated as per equation is written above)
Case2: power factor of 1 (unity)
Here, the value of kVA required is 100 kVA. Which is less than the previous case. This indicates that the kVA demand decreases if power factor of my equipment increases.
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86.In an induction motor, no-load the slip is generally
a- 5%
b- 4%
c- 2%
d- Less than 1%
Answer :
87.The shaft of an induction motor is made of
a- Stainless steel
b- Cast iron
c- Carbon steel
d- Aluminium
Answer :
88.The efficiency of an induction motor is about
a- 100%
b- 80-90%
c- Less than 50%
d- Less than 50%
Answer :
89.A double squirrel-cage induction motor has
a- Two series winding in the stator
b- Two rotors moving in the opposite direction
c- Two parallel windings in the stator
d- Two parallel winding in Rotor
Answer :
90.Which of the following number specification refers to FET with one gate
a- 2N
b- 3N
c- 3Y
d- 3X
Answer :
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91.MOSFET has input impedence of
a- 100 mega ohm
b- 1 ohm
c- 10 ohm
d- 0 ohm
e- Non of the above
Answer :
92.Which junction is preferred for high input and low output impedance
a- CE
b- CB
c- CC
d- Any of the above
Answer :
93.The operation of JEFT involves
a- Flow of minority carriers
b- Flow of majority carriers
c- Flow of both the carriers
d- None of the above
Answer :
94.A Quiescent state of a transistor implies
a- 0 bias
b- No output
c- No distrotion
d- No input signal
Answer :
95.Which amplifier operates with least distrotion
a- Class A
b- Class B
c- Class C
d- Class D
Answer :
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96.Leakage current in CE confugration is around
a- Few nano amps
b- Few micro amps
c- Few hundred micro amps
d- Few milli amps
Answer :
97.Bjt is a....... Controlled device, where as FET is a...... Controlled device
a- i, v
b- v, i
c- i, i
d- v, v
Answer :
98.Each of two Cascade stages has a voltage gain of 30. The overall gain is
a- 3
b- 9
c- 30
d- 900
Answer :
99.The properties of JEFT resembles
a- Thermonic valves
b- NPN transistor
c- PNP transistor
d- UJT
Answer :
100.Highest operating frequency can be obtained in case of
a- FET
b- JFET
c- BJT
d- MOSFET
Answer :
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101.Which of the following circuits can operate class AB for audio power output
a- Emitter follower
b- Pushpull
c- Cascade
d- Darlington pair
Answer :
102.Circuit breakers usually operate under
1.Transient state of short-circuit current
2.Sub-transient state of short-circuit current
3.The steady state of short-circuit current
4.After D.C. component has ceased
Answer :
103.Arc in a circuit behaves as
A- A capacitive reactance
B- An inductive reactance
C- A resistance increasing with voltage rise across the arc
D- A resistance decreasing with voltage rise across the arc
Answer :
104.Deflection torque can be produced by
a- Gravity control
b- Spring control
c- Air control
d- Magnetically
Answer :
105.3 Resistor of equal value when connected in series with supply have a power loss of 90W and when they are connected in parallel they would have power loss of?
a- 270W
b- 30W
c- 90W
d- 810W
e- None of the above
Answer :
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106.Which of the following statements is correct
Equipotential lines and field lines
a- Are paralle
b- Are anti parallel
c- Are orthogonal
d- Bear no definite relationship
Answer :
107.Where laplace equation valid
a- Only in free space
b- Only in conductors
c- Only in charge free dielectric regions
d- Only in cavities bounded on all sides by conducting walls
Answer :
108.Which of the following is a vector quantity
a- Magnetic potential
b- Susceptibility
c- Magnetic field intensity
d- Magnetic flux density
Answer :
109.An ideal voltage source will charge an ideal capacitor
a- Infinite time
b- Exponentially
c- Instantaneously
d- None of the above
Answer :
110.Who developed the concept of time varying electric field producing a magnetic field
a- Gauss
b- Faraday
c- Hertz
d- Maxwell
Answer :
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111.The magnitude of magnetic field strength H is independent of
a- Current only
b- Distance only
c- Permeability of medium only
d- Both distance and current
Answer :
112.Which of the following quantities consists of S.I. unit as Hertz?
a- Charge
b- Force
c- Frequency
d- Power
Answer :
113.Which one of the following units is a fundamental unit
a- Newton
b- Ampere
c- Watt
d- Joule/sec
Answer :
114.What is the approximate efficiency of a normal thermal power station ?
a) 30-40%
b) 45-55
c) 20-25%
d) 60-70%
Answer :
115.What is the approximate efficiency of a normal thermal power station ?
a) 30-40%
b) 45-55
c) 20-25%
d) 60-70%
Answer :
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116.The advantage of hydro electric power station over thermal power station is
a) The initial cost of hydro electric power station is low
b) The operation cost of hydro electric power station is low
c) Hydro electric power station can supply the power throughout the year
d) Hydro electric station can be constructed at the place where the energy is required
Answer :
117.In which of the following frequency control method tie line may be overloaded
a) Flat frequency control
b) Flat tie line control
c) Parallel frequency
d) All of the above
Answer :
118.Which of the following statements is/are true ?
a) A thermal reactor needs a moderator materiel
b) In nuclear reactor, mltiplication factor is kept almost equal to one
c) Nuclear power plants are used as peak load plants only
d) Both 1 and 2
Answer :
119.Demand factor of a plant is
a) 0
b) 1
c) Less then 1
d) Greater then 1
Answer :
120.The economics of power plant is greatly influenced by
a) Load factor
b) Diversity factor
c) Both 1 and 2
d) Nether 1 nor 2
Answer :
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121.Pelton turbine is a.......turbine
a) Axial flow
b) Inword radial flow
c) Impulsive
d) any of the above
Answer :
122.Which of the following is low specific speed turbine ?
a) Pelton
b) Kaplan
c) Francis
d) Non of the above
Answer :
123.For variable heads of near about but less then 30 meters, which type of turbine is used in hydro power station ?
a) Pelton
b) Kaplan
c) Francis
d) Non of the above
Answer :
124.More efficient plants are used as
a) Base load plant
b) Peak load plant
c) Both 1 and 2
d) Non of the above
Answer :
125.Which of the following statement is/are true regarding infinite line ?
a) It has infinite length
b) It has infinite voltage
c) It maintains the constant voltage
d) Both 2 and 3
Answer :
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126.In thermal power stations, economiser will
a) Increase the thermal efficiency
b Reduce the thermal efficiency
c) Reduce the Heat
d) both 2 and 3
Answer :
127.pulversed coal is
a) Coal free from ash
b) Non smoking coal
c) Coal which bums for long time
d) Coal broken into fine particles
Answer :
128.Which of the following is considered as superior Quality of coal ?
a) Bituminous coal
b) Peat
c) lignite
d) coke
Answer :
129.Which of the following is neglected while analyzing a short transmission line?
a) Power losses
b) Shunt admittances
c) Series impedance
d) None of these
Answer :
130.Following effects are associated with transmission lines
1. Skin effect
2. Corona effect
3. Proximity effect The effective resistance of conductor is increased by
a) 1 only
b) 2 and 3 only
c) 1 and 3 only
d) 1,2 and 3
Answer :
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131.Shunt capacitance is neglected in case of
a) Medium and long transmission lines
b) Long transmission lines
c) Medium transmission lines
d) Short transmission lines
Answer :
132.When a 15 V input pulse with a width equal to two time constants is applied to an RC integrator, the capacitor charges to
A. 15 V
B. 12.9 V
C. 8.6 V
D. 19.45 V
Answer :
133.An inductance of 0.08 H is larger than
A. 0.0000008 H
B. 0.000000008 H
C. 0.000008 H
D. 0.00008 mH
Answer :
134.A 240 H inductor is equivalent to a
a- 0.240 mH inductor
b- 0.000240 mH inductor
c- 240 mH inductor
d- 240 H inductor
Answer :
135.The permeability of a core material is an indication of the ability of the material to establish a magnetic field.
a True
B. False
Answer :
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136.XL is directly proportional to frequency and inductance.
A. True
B. False
Answer :
137.An induced voltage is produced as a result of a dc voltage.
A. True
B. False
Answer :
138.Faraday's law states that relative motion between a magnetic field and a coil induces a voltage across the coil.
A. True
B. False
Answer :
139.Inductance is the property of an inductor that produces an opposition to any change in current.
A. True
B. False
Answer :
140.All coil cores are made of iron.
A. True
B. False
Answer :
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141.Inductance is indirectly proportional to the square of the number of turns, the permeability, and the cross-sectional area of the core.
A. True
B. False
Answer :
142.Some factors that affect the inductance of a coil include:
1. The inductance is proportional to the square of the number of turns;
2. The inductance increases directly as the permeability of the core material increases;
3. The inductance increases directly as the cross-sectional area increases; and
4. The inductance decreases as its length increases.
Answer :
143.Inductors add in parallel.
A. True
B. False
Answer :
144.XC is inversely proportional to frequency and capacitance.
A. True
B. False
Answer :
145.why we subscribe this channel ...,because
a- we want all time mcq on this channel
b- thanks for giving me mcq
c- we are always support to this channel
d- it is helful for competitive exam
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146.Voltage leads current by 90° in a capacitor.
A. True
B. False
Answer :
147.The dielectric constant is the ability of a material to establish an electric field.
A. True
B. False
Answer :
148. subscribe electrical engineering channel for all time mcq
a- yes
b- if u subscribe i will provile all time mcq
c- no ..we dont want all time mcq
d- subscribe fast
Answer :
149.Total parallel capacitance is less than that of the smallest capacitor in parallel.
A. True
B. False
Answer :
150.The ohm is the unit of capacitance
A. True
B. False
Answer :
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151.Five time constants are required for a capacitor to charge fully or discharge fully.
a- True
b- False
Answer :
152.Capacitance is directly proportional to plate area and plate separation.
A. True
B. False
Answer :
153.The true power in a capacitor is zero.
A. True
B. False
Answer :
154.A capacitor blocks ac but passes dc.
A. True
B. False
Answer :
155.Energy is stored by a capacitor in a magnetic field.
A. True
B. False
Answer :
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156.When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
a- increases
b- decreases
c- remains constant
d- reaches zero
Answer :
157.Lenz's law defines the polarity of the induced voltage.
A. True
B. False
Answer :
158.A magnetic field is made up of flux lines.
A. True
B. False
Answer :
159.Hysteresis is the number of lines of force per unit area in a magnetic field.
A. True
B. False
Answer :
160.Materials with a low retentivity do not retain a magnetic field very well.
A. True
B. False
Answer :
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161.The formula for finding voltage when resistance and current are known is V = I/R.
A. True
B. False
Answer :
162.The ampere is the unit of resistance.
A. True
B. False
Answer :
163.If an open capacitor is checked with an ohmmeter, the needle will:
A. stay on zero
B. stay on infinity
C. move from zero to infinity
D. move from infinity to zero
Answer :
164.Determine the resistance (in ohms) of a 14 m long circular wire when the diameter and the conductivity of the wire are 0.6 m and 12 mho/meter respectively.
1. 1.79
2. 2.84
3. 3.64
4. 4.17
Answer :
165.Kirchhoff s current law states that
a- net current flow at the junction is positive
b- algebraic sum of the currents meeting at the junction is zero
c- no current can leave the junction without some current entering it
d- total sum of currents meeting at the junction is zero
Answer :
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166.According to Kirchhoffs voltage law, the algebraic sum of all IR drops and e.m.fs. in any closed loop of a network is always
(a) negative
(b) positive
(c) determined by battery e.m.fs.
(d) zero
Answer :
167.Kirchhoffs current law is applicable to only
a- junction in a network
b- closed loops in a network
c- electric circuits
d- electronic circuits
Answer :
168.A passive network is one which contains
A. Only variable resistance
B. Only some sources of e.m.f. in it
C. Only two sources of e.m.f. in it
D. No source of e.m.f. in it
Answer :
169.A network which contains one or more than one source of e.m.f. is known as
A. Linear network
B. Non-linear network
C. Passive network
D. Active network
Answer :
170.In non-linear network does not satisfy
A. Superposition condition
B. Homogeneity condition
C. Both homogeneity and superposition condition
D. Homogeneity, superposition and associative condition
Answer :
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171.The number of independent equations to solve a network is equal to
A. The number of chords
B. The number of brunches
C. Sum of the number of branches and chords
D. Sum of the number of branches, chords and nodes
Answer :
172.A closed path made by several branches of the network is known as
a- Branch
b- Loop
c- Circuit
d- Junction
Answer :
173.A network has 10 nodes and 17 branches. The number of different node pair voltage would be
A. 7
B. 9
C. 45
D. 10
Answer :
174.Pole of a network is a frequency at which
A. Network function becomes zero
B. Network function becomes infinity
C. Network function becomes unity
D. None of these
Answer :
175. A circuit having neither any energy source nor e.m.f. source is called the .........circuit
A. Unilateral
B. Bilateral
C. Passive
D. Active
Answer :
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176.Which of the following is an active element in a circuit?
A. Current source
B. Resistance
C. Inductance
D. Capacitance
Answer :
177.Which of the following is not a bilateral element ?
A. Constant current source
B. Resister
C. Inductor
D. capacitor
Answer :
178.The elements which are not capable of delivering energy by its own are known as
a- Unilateral elements
b- Nonlinear elements
c- Passive elements
d- Active elements
Answer :
179.To neglect a voltage source, the terminals across the source are
A. Open-circuited
B. Short-circuited
C. Replaced by some resistance
D. Replaced by inductor
Answer :
180.For determining the polarity of a voltage drop across a resistor, it is necessary to know the
a- Value of resistor
b- Value of current
c- Direction of current flowing through the resistor
d- Value of e.m.f. in the circuit
Answer :
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181.Which of the following is the passive element ?
A. Capacitance
B. Ideal current source
C. Ideal voltage source
D. All of the above
Answer :
182.Which of the following is not a non-linear element?
A. Gas diode
C. Tunnel diode
B. Heater coil
D. Electric arc
Answer :
183.If the frequency of an alternator increase then
a- Its speed decreases
b- Its speed increases
c- None of the above
d- Speed will remain constant
Answer :
184.In gases the flow of current is due to
a- Electrons only
b- Positive ions only
c- Electrons and positive ions
d- Electrons, positive ions and negative ions
Answer :
185.The minimum requirements for causing flow of current are
a- A voltage source, a resistor and a switch
b- A voltages source and a conductor
c- . A power source and a bulb
d- A voltage source, a conductor an ammeter and a switch
Answer :
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186.What is switchgear?
a- An apparatus used for switching, controlling and protecting the electrical circuits and equipments
b- It detects the faults only
c- It corrects the faults only.
d- All of above
Answer :
187.A 2 ohms resistor having 1 ampere current will dissipate the power of
a) 2 Watts
b) 2 Joules
c) 1 Watt
d) 1 Joule
Answer :
188.Thevenin’s equivalent circuit can be used to calculate the power loss in the original circuit.
a) True
b) False
Answer :
189.Transient response in the system is basically due to
a) Forces
b) Friction
c) Stored energy
d) Coupling
Answer :
190.Effect of feedback on the plant is to
a) Control system transient response
b) Reduce the sensitivity to plant parameter variations
c) Both (a) and (b)
d) None of these
Answer :
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191.Transfer function of a system is defined as the ratio of output to input in
a) Z-transformer
b) Fourier transform
c) Laplace transform
d) All of these
Answer :
192.Transfer function of a system can used to study its
a) Steady state behavior
b) Transient behavior
c) Both (a) and (b)
d) None of these
Answer :
193.A bridge used for the measurement of capacitance is
d- Wheatstone bridge
a- Wein bridge
b- Maxwell bridge
c- Schering bridge
Answer :
194.The Percentage slip in synchronous motor is
a- 0.01
b- 1
c- 0.005
d- Zero
Answer :
195.Which motor is used in signaling devices ?
a- DC series motor
b- Reluctance motor
c- DC shunt motor
d- Hysteresis motor
Answer :
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196.Brake test for determination of efficiency of a DC machine is ... ?
a- An indirect method
b- A regenerative method
c- A direct method
d- None
Answer :
197.Stepped core is used in transformer in order to reduce?
c - Volume of iron
a- Volume of copper
b- Iron loss
d- Reluctance of core
Answer :
198.Commutation conditions at full load for large DC machines can be efficiently checked by ?
a- Brake test
b- Swinburne's test
c- Hopkinson's test
d- Field test
Answer :
199.Maximum temperature for class F insulation is ?
a- 130°C
b- 120°C
c- 105°C
d- 155°C
Answer :
200.The largest size of steam turbine installed in India is
a- 100 MW
b- 250 Mw
c- 500 MW
d- None of the abobe
Answer :
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201.In Hydro stations, for slow specific speeds that in 4 - 70 RPM range which of the following is turbine is used
a- Pelton
b- Francis
c- Kaplan
d- Propeller
Answer :
202.Rotor used in alternators of hydro electric station is
a- Cylindrical rotor
b- Salient pole rotor
c- Non salient pole rotor
d- Round rotor with ac excitation
Answer :
203.The force between two charges is 120 N. If the distance between the charges is doubled, the force will be
a) 60 N
b) 30 N
c) 40 N
d) 15 N
Answer :
204.The electric field intensity at a point situated 4 meters from a point charge is 200 N/C. If the distance is reduced to 2 meters, the field intensity will be
(a) 400 N/C
(b) 600 N/C
(c) 800 N/C
(c) 800 N/C
Answer :
205.The lines of force due to charged particles are
(a) always straight
(b) always curved
(c) sometimes curved
(d) none of the above
Answer :
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206.The electric field at a point situated at a distance d from straight charged conductor is
(a) proportional to d
(b) inversely proportional to d
(c) inversely proportional to d
(c) inversely proportional to d
Answer :
207.The direction of electric field due +0 positive charge is .
(a) away from the charge
(b) towards the charge
(c) both (a) and (b)
(d) none of the above
Answer :
208.A field line and an equipotential surface are
(a) always parallel
(b) always at 90°
(c) inclined at any angle 0
(d) none of the above
Answer :
209.The ability of charged bodies to exert force on 6ne another is attributed to the existence of -
(a) electrons
(b) protons
(c) neutrons
(d) electric field
Answer :
210.If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will - (a) decrease
(b) increase
(c) remains unchanged
(d) become zero
Answer :
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211. A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is
(a) 0.024 F
(b) 0.12 F
(c) 0.6 F
(d) 0.8 F
Answer :
212.For making a capacitor, it is better to select a dielectric having
(a) low permittivity
(b) high permittivity
(c) permittivity same as that of air
(d) permittivity slightly more than that of air
Answer :
213.Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air.What will be the value of dielectric constant ?
(a) 50
(b) 100
(c) 150
(d) 200
Answer :
214.In a capacitor the electric charge is stored in -
(a) metal plates
(b) dielectric
(c) both (a) and b)
(d) none of the above
Answer :
215.Which of the following capacitors will have the least variation ?
(a) Paper capacitor
(b) Ceramic capacitor
(c) Silver plated mica capacitor
(d) None of the above
Answer :
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216.The power dissipated in a pure capacitor is
(a) zero
(b) proportional to applied voltage
(c) proportional to value of capacitance
(d) both (b) and (c) above
Answer :
217.In a capacitive circuit
(a) a steady value of applied voltage causes discharge
(b) an increase in applied voltage makes a capacitor charge
(c) decrease in applied voltage makes a capacitor charge
(d) none of the above
Answer :
218.When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between
plates will
(a) remain uncharged
(b) decrease
(c) increase
(d) become zero
Answer :
219.Capacitance increases with
(a) increase in plate area and decrease in distance between the plates
(b) increase in plate area and distance between the plates
(c) decrease in plate area and value of applied voltage
(d) reduction in plate area and distance between the plates
Answer :
220.A capacitor consists of
(a) two insulators separated by a conductor
(b) two conductors separated by an insulator
(c) two insulators only
(d) two conductors only
Answer :
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221.A paper capacitor is usually available in the form of
(a) tubes
(b) rolled foil
(c) disc
(d) meshed plates
Answer :
222.The unit of capacitance is
(a) henry
(b) ohm
(c) farad
(d) farad/m
Answer :
223.A capacitor in a circuit became hot and ultimately exploded due to wrong connections, which type of capacitor it could be ?
a) Paper capacitor
b) Ceramic capacitor
c) Electrolytic capacitor
d) Any-of the above
Answer :
224.The relative permittivity of free space is given by
(a) 1
(b) 10
(c) 100
(d) 1000
Answer :
225.When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of
(a) 2 joules
(b) 4 joules
(c) 6 joules
(d) 8 joules
Answer :
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226.Which capacitor will be physically smaller for the same ratings ?
(a) Ceramic capacitor
(b) Paper capacitor
(c) Both will be of equal size
(d) None of the above
Answer :
227.Which of the following material has least value of dielectric constant ?
(a) Ceramics
(b) Oil
(c) Glass
(d) Paper
Answer :
228.Which of the following capacitors can be used for temperature compensation ?
(a) Air capacitor
(b) Ceramic capacitor
(c) Paper capacitor
(d) None of the above
Answer :
229.Paper capacitors usually have a tolerance of
(a) ± 5%
(b) ± 10%
(c) ± 15%
(d) ± 20%
Answer :
230.For closer tolerances which of the following capacitors is usually preferred ?
(a) Paper capacitor
(b) Mica capacitor
(d) None of the above
(c) Ceramic disc capacitor
Answer :
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231.In which of the following reason induction motor operation is stable?
a- Any of two
b- Low slip region
c- High slip region
d- None of the above
Answer :
232.If a transformer is continuously operated the maximum temperature rise will occur in -
(a) core
(b) windings
(c) tank
(d) any of the above
Answer :
233.The hum in a transformer is mainly attributed to
(a) load changes
(b) oil in the transformer
(c) magnetostriction
(d) mechanical vibrations
Answer :
234.The maximum load that a power transformer can carry is limited by its
(a) temperature rise
(b) dielectric strength of oil
(c) voltage ratio
(d) copper loss
Answer :
235.The efficiency of a transformer, under heavy loads, is comparatively low because
(a) copper loss becomes high in proportion to the output
(b) iron loss is increased considerably
(c) voltage drop both in primary and secondary becomes large
(d) secondary output is much less as compared to primary input
Answer :
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236.An open-circuit test on a transformer is conducted primarily to measure
(a) insulation resistance
(b) copper loss
(c) core loss
(d) total loss
(e) efficiency
(f) none of the above
Answer :
237.A no-load test is performed on a transformer to determine - (a) core loss
(b) copper loss
(c) efficiency
(d) magnetising current
(e) magnetising current and loss
Answer :
238.If a transformer is switched on to a voltage more than the rated voltage -
(a) its power factor will deteriorate
(b) its power factor will increase
(c) its power factor will remain unaffected
(d) its power factor will be zero
Answer :
239.Minimum voltage regulation occurs when the power factor of the load is
(a) unity
(b) lagging
(d) zero
(c) leading
Answer :
240.The efficiencies of transformers compared with that of electric motors of the same power are - a . about the same
(a) much smaller
(b) much higher
(c) somewhat smaller
(d) somewhat smaller
Answer :
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241.Off-circuit tap changer is used when transformer is ________________
a) deenergized
b) energized
c) can be used in either energy conditions
d) never used
Answer :
Q242.. The thickness of lamination in D.C machine is approx
a-5 mm
b-0.5 mm
c-0.005 mm
d-5 mm
Answer :
1.According to Faraday’s law of electromagnetic induction rotating armature cuts the magnetic field, due to which an emf is induced in it.2.This emf generate the eddy current which causes eddy current loss.
3.Therefore to reduce the effect of eddy current the armature core is laminated.
4.The thickness of lamination is between 0.1 to 0.5 mm.
Q243.The resistance of armature winding depends upon
a-Length of conductor
b-Cross sectional area of conductor
c-Number of conductors
d-Any of the above
Answer :
explanation:
There are four factors that influence the resistance in a conductor.
⇒Thickness (cross sectional area of the wire). (R ∝ 1/A)
⇒Length ( R ∝ L)
⇒Temperature
⇒Conductivity of material
The number of armature conductor “Z” is constant that depends upon the number of turns on the armature and the type of winding. i.e wave winding or lap winding.
244.Are you satisfied for today's quiz on dc generator
a- 100%
b- 75%
c- 50%
d- 25%
Answer :
245.The resistivity of a conductor depends upon (SSC 2018 -S-1)
a- Pressure
b- Temperature
c- Degree of Illumination
d- Shape of cross-section
Answer :
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246. What will be the equivalent capacitance (in mF) of three capacitors connected in a series having the capacitance of 0.04 mF, 0.08 mF, and 0.02 mF respectively? (SSC 2018 -S-1)
a- 0.026
b- 0.032
c- 0.065
d- 0.011
Answer :
247.If the area, current, and the number of turns of an AC circuit is doubled, then the new inductance will be:-
a- Twice the former
b- Four Times the former
c- Small
d- Half the former
Answer :
248.If the total number of slots in a D.C machine is 25 and the total number of poles is 5, then what is the coil span of the machine?
a- 5
b- 30
c- 20
d- 125
Answer :
249.Calculate the energy efficiency when the input energy is 3000J and output energy is 1000J.
a- 0.5
b- 0.5
c- 0.5
d- 0.333
Answer :
250.The ________ region has the highest area in the transistor
a- Collector
b- Base
c- Base-Emitter
d- Base-Emitter
Answer :
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251.The circuit breaker is a device that is used for protection of circuit. The circuit breaker is an example of:
a- Arresters
b- Conductor
c- Switchgear
d- None of these
Answer :
252.To save energy during braking which type of Braking is used?
a- Regenerative
b- Plugging
c- Dynamic
d- All of these
Answer :
253.For similar carrier and modulating signals, the line current used in CSI is_____________?
A. Identical to line voltage in a VSI
B. Identical to line current in VSI
C. Identical to phase voltage in VSI
D. Identical to phase voltage in CSI
Answer :
254.With rise in temperature the resistance of semi-conductors_________________?
A. decreases
B. increases
C. first increases and then decreases
D. remains constant
Answer :
255.Two resistors are said to be connected in series when___________?
A. same current passes in turn through both
B. both carry the same value of current
C. total current equals the sum of branch currents
D. sum of IR drops equals the applied e.m.f.
Answer :
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256.Which of the following statement is true both for a series and a parallel D. C. circuit?
A. Elements have individual currents
B. Currents are additive
C. Voltages are additive
D. Power are additive
Answer :
257.Which of the following materials has a negative temperature co-efficient of resistance?
A. Copper
B. Aluminium
C. Carbon
D. Brass
Answer :
258.The substances which have a large number of free electrons and offer a low resistance are called____?
A. insulators
B. inductors
C. semi-conductors
D. conductors
Answer :
259.Out of the following which is not a poor conductor__________?
A. Cast iron
B. Copper
C. Carbon
D. Tungsten
Answer :
260.A 3-phase 4 wire system is commonly used on________________?
A. primary transmission
B. secondary transmission
C. primary distribution
D. secondary distribution
Answer :
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261.There is a greater possibility of occurrence of corona during______________?
A. dry weather
B. winter
C. summer heat
D. humid weather
E. none of the above
Answer :
262.Which of the following is not a constituent for making porcelain insulators ?
A. Quartz
B. Kaolin
C. Feldspar
D. Silica
Answer :
263.Which of the following materials is used for overhead transmission lines ?
A. Steel cord aluminium
B. Galvanised steel
C. Cadmium copper
D. Any of the above
Answer :
264.The power transmitted will be maximum when____________?
A. corona losses are minimum
B. reactance is high
C. sending end voltage is more
D. receiving end voltage is more
Answer :
265The steel used in steel cored conductors is usually
A. Alloy steel
B. Stainless steel
C. Mild steel
D. High speed steel
Answer :
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266.. By which of the following systems electric power may be transmitted ?
(a) Overhead system
(b) Underground system
(c) Both (a) and (b)
(d) None of the above
Answer :
267.When a live conductor of public electric supply breaks down and touches the earth which of the
following will happen ?
(a) Current will flow to earth
(b) Supply voltage will drop
(c) Supply voltage will increase
(d) No current will flow in the conductor
(e) None of the above
Answer :
268.When a conductor carries more current on the surface as compared to core, it is due to
(a) permeability variation
(b) corona
(c) skin effect
(d) unsymmetrical fault
(e) none of the above
Answer :
269.The voltage regulation in magnetic amplifier type voltage regulator is effected by
(a) electromagnetic induction
(b) varying the resistance
(c) varying the reactance
(d) variable transformer
Answer :
270.Series capacitors on transmission lines are of little use when the load VAR requirement is
(a) large
(b) small
(b) fluctuating
(d) any of the above
Answer :
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271.The voltage of the single phase supply to residential consumers is
(a) 110 V
(b) 210 V
(c) 230 V
(d) 400 V
Ans:
272.Most of the high voltage transmission lines in India are
(a) underground
(b) overhead
(c) either of the above
(d) none of the above
Answer :
273.The distributors for residential areas are
(a) single phase
(b) three-phase three wire
(c) three-phase four wire
(d) none of the above
Answer :
274.Besides a method of trial and error, which of the following methods is employed for solution of
network problems in interconnected system ?
(a) Circulating current method
(b) Thevenin's theorem
(c) Superposition of currents
(d) Direct application of Kirehhoffs laws
(e) All of the above
Answer :
275.A booster is a
(a) series wound generator
(b) shunt wound generator
(c) synchronous generator
(d) none of the above
Answer :
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276.Which of the following D.C. distribution system is the simplest and lowest in first cost ?
(a) Radial system
(b) Ring system
(c) Inter-connected system
(d) None of the above
Answer :
277.Due to which of the following reasons the cables should not be operated too hot ?
(a) The oil may loose its viscosity and it may start drawing off from higher levels
(b) Expansion of the oil may cause the sheath to burst
(c) Unequal expansion may create voids in the insulation which will lead to ionization
(d) The thermal instability may rise due to the rapid increase of dielectric losses with temperature
(e) All of the above
Answer :
278.The operating voltage of extra high tension cables is upto
(a) 6.6 kV
(b) 11 kV
(c) 33 kV
(d) 66 kV
(e) 132 kV
Answer :
279.The operating voltage of supertension cables is up to
(a) 3.3 kV
(b) 6.6 kV
(c) 11 kV
(d) 33 kV
Answer :
280.The square root of the ratio of line impedance and shunt admittance is called the
a- surge impedance of the line
b- conductance of the line
c- regulation of the line
d- none of the above
Answer :
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281.The ideal load factor should be
a- 1
b- 0.5
d- 0.2
c- 0.8
Answer :
282.The base load power station supplies load ……...in a day
a- 10 hours
b- 16 hours
c- 24 hours
d- 12 hours
Answer :
283.The auto-starters (using three autotransformers) can be used to start cage induction motor of the following type
a- Star and Delta connected
b- None
c- Delta connected only
d- Star connected only
Answer :
284.In a three-phase induction motor, the number of poles in the rotor winding is always
a- Less than the number of poles in the stator
b- Equal to the number of poles in the stator
c- More than the number of poles in the stator
d- Zero
Answer :
285.The shaft of an induction motor must be of
a- Flexible
b- Any of the above
c- Hollow
d- Solid
Answer :
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286.The auto-starters (using three autotransformers) can be used to start cage induction motor of the following type
a- Star and Delta connected
b- None
c- Delta connected only
d- Star connected only
Answer :
287.The size of the synchronous motor decrease with the increase in:-
c- Speed
a- Flux density
b- Horsepower rating
d- All of these
Answer :
288.If the area, current, and the number of turns of an AC circuit is doubled, then the new inductance will be
a- Twice the former
b- Four Times the former
c- Small
d- Half the former
Answer :
289.Iron losses in a D.C. machine are independent of variations in
(a) speed
(b) load
(c) voltage
(d) speed and voltage
Answer :
290.In D.C. generators, current to the external circuit from armature is given through -
(a) commutator
(b) solid connection
(c) slip rings
(d) none of above
Answer :
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291.Brushes of D.C. machines are made of
(a) carbon
(b) soft copper
(c) hard copper
(d) all of above
Answer :
292.Armature reaction of an unsaturated D.C. machine is
(a) crossmagnetising
(b) demagnetising
(c) magnetising
(d) none of above
Answer :
293.The fuse wire is made of
A) nichrome
B) copper
C) lead tin alloy
D) aluminum
Answer :
294.The transformer oil should have _____ Volatility and _____ Viscosity.
a- Low & High
b- High & High
c- Low & Low
d- High & Low
Answer :
295.During open circuit test of a transformer
a- Primary is supplied rated voltage
b- Primary is supplied current at reduce voltage
c- Primary is supplied rated KVA
d- Primary is supplied full load current
Answer :
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296.Which type of winding is used in 3-phase shell type transformer
a- Rectangular Type
b- Cylindrical Type
c- Sandwich Type
d- Circular type
Answer :
297.The transformer laminations are insulated from each other by
a- Mica strip
b- Paper
c- Thin coating of Varnish
d- Any of the above
Answer :
298.Two transformer is connected in parallel. These transformer have different percentage impedance. These is likely to result in
a- Loading in the transformer is not proportional to their KVA rating.
b- Short circuit in secondary
c- Higher copper loss
d- Power factor of one of the transformer is leading while that of the other is lagging.
Answer :
299.Which of the following is the main advantage of auto transformer over a two winding transformer?
a- Reduces hysteresis losses
b- Reduce eddy current losses
c- Copper losses are negligible
d- Saving of copper material
Answer :
300.Which winding of the transformer has less cross section area?
a- Primary winding
b- Secondary Winding
c- High Voltage Winding
d- Low Voltage Winding
Answer :
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301.The core used in high frequency transformer is usually
a- Copper Core
b- Mild Steel Core
c- Air core
d- Iron Core
Answer :
302.Harmonics in transformer result in
a- Increase core losses
b- Increases I2R Losses
c- Interference with communication circuits
d- All of the above
Answer :
303.Stones are provided in the substation to
a- To provide insulation
b- To avoid Fire accident during leakage of transformer oil
c- To avoid growing of plants and weed
d- All of the above
Answer :
304.Cruciform shape is used in transformer core to
a- Reduce core loss
b- Reduce core reluctance
c- Reduce winding copper
d- All of the above
Answer :
305.Which of the following test is performed to determine the leakage reactance
a- Short circuit test
b- Open circuit test
c- Both Open circuit and short circuit test
d- Test by an Impedance bridge
Answer :
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306.During SC test the Power Input to a transformer comprises predominately
a- Core loss
b- Copper loss
c- Hysteresis loss
d- Eddy current loss
Answer :
307.The maximum load that a power transformer can carry is limited by its
a- Voltage ratio
b- Temperature Rise
c- Cooper Loss
d- Dielectric strength of coil
Answer :
308.A shell type transformer has
a- High eddy current losses
b- Reduce magnetic leakage
c- Low hysteresis losses
d- All of the above
Answer :
309.A transformer can have zero voltage regulation closer to zero
a- On full load
b- On overload
c- On leading power factor
d- On zero power factor
Answer :
310.The size of the transformer core mainly depends on
a- Frequency
b- Area of core
c- Flux density of core
d- Both frequency and area of core
Answer :
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311.If we increase the length of the transmission line, the charging current
a- increases
b- decreases
c- remains unaffected
d- none of the above
Answer :
312.Ampere is used to measure
a- Temperature
b- Current
c- Light
d- Weight
Answer :
313.The electric susceptibility of the vacuum is
a- Positive
b- Negative
c- Zero
d- One
Answer :
314.A no-load test is performed on a transformer to determine
d- Magnetizing current only
c- Core losses only
b- Efficiency
a- Magnetizing current and losses
Answer :
315.When two waves of same frequency and same amplitude traveling in opposite directions in a straight line overlap the give rise to:
a- Beats
b- Interference
c- Stationary Wave
d- Harmonics
Answer :
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316.The unit of luminous intensity is
a- Lumen
b- Lux
c- Candela
d- Watt
Answer :
317.For energy sensitive and wide speed control, the preferred control method is
a- Armature control
b- Ward Leonard control
c- Multiple voltage control
d- Field control
Answer :
318.Which of the following materials is used for the permanent magnets?
a- Bras
b- Copper
d- Copper
c- Steel
Answer :
319.Transport of charge carrier in the semiconductor is achieved through
a- Conduction and Diffusion
b- Conduction
c- Diffusion
d- None of these
Answer :
320.Which among the below-mentioned reasons is/are responsible for the occurrence of second breakdown phenomenon is power BJT?
a- Large current
b- Distribution of current in a non-uniform manner
c- Excessive power dissipation
d- All of the above
Answer :
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321.The main function of a transformer is to change
a- Power
b- Frequency
d- Voltage Level
c- Power factor
Answer :
322.Which of the following is a cold cathode lamp?
a- Sodium lamp
b- Neon Lamp
c- CSL Lamp
d- Tubelight
Answer :
323.The V.I characteristics of the diode lie in the
a- 1st and 2nd Quadrant
b- 1st and 3rd Quadrant
c- 1st and 4th Quadrant
d- Only in 1st Quadrant
Answer :
324.Which of the following is used in a semiconductor device?
a- Silicon
b- Graphite
c- Copper
d- Aluminum
Answer :
325.Generator transformer are
a- Step-up transformer
b- Step-down transformer
c- Auto transformer
d- One-one transformer
Answer :
Explanation:-
A step-up transformer associated with the turbine generator systems is called a generator transformer. Its role is to raise the voltage of the electric energy generated which can be efficiently transmitted to the substation via buried cables or overhead lines. Generator transformers step the voltage up from the generator level of typically 10-20 kV to the transmission or sub-transmission voltage.
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326.Two electric bulbs designed to operate with a power of 500 watts in 220-volt line are connected in series with a 110 volt line. The power generated by each bulb will be
a- 31.25 watts
b- 3.125 watts
c- 22 watts
d- 62.5 watts
Answer :
Explanation:-
Given
P = Power = 500 W
Voltage V = 220 volt
Resistance R =
The power is given as
P = V2/R
500 = (220)2/R
R = 96.8 ohms
Now bulb is connected to 110 V supply. Therefore power will be
P = V2/R
P = (110)2/96.8
P = 125 watts
Hence power generated by each bulb as they are connected in series will be
P = 125/2 = 62.5 watts
327.The resistance of an ideal ammeter is
a- Low
b- High
c- Infinite
d- Zero
Answer :
328.Power factor can be improved by connecting which among the following?
a- 1 Static capacitor
b- 2 Resistor
c- 3 Synchronous condenser
d- 4 Both 1 and 3
Answer :
329.Which of the following rotor is used in thermal power plants?
a- Cylindrical rotor
b- Salient pole rotor
d- Either of these
c- Square cage rotor
Answer :
330.In a three-phase induction motor, the number of poles in the rotor winding is always
A. Zero
B. More than the number of poles in stator
C. Less than number of poles in stator
D. Equal to number of poles in stator
Answer:
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331.. In a three-phase induction motor, the number of poles in the rotor
winding is always
(a) zero
(b) more than the number of poles in stator
(c) less than number of poles in stator
(d) equal to number of poles in stator
Answer :
332.In a three-phase induction motor, the number of poles in the rotor winding is always
A. Zero
B. More than the number of poles in stator
C. Less than number of poles in stator
D. Equal to number of poles in stator
Answer :
333.Shunt, series and compound generators are the types of __.
A.Separately excited generators
B.Self-excited generators
C.Long shunt differential compound generators
D.short shunt differential compound generators
Answer :
334.Varistors are -
A) resistor with zero temperature coefficient
B) insulator
C) non linear resistor
D) carbon resistor
Answer :
335.Stator of alternator is identical to
a- Dc machine
b- 3phase induction motor
c- 1 phase induction motor
d- None
Answer :
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336.Maximum torque of induction motor is
a- 2-3 times full load torque
b- 1.5 times full load
c- 7 times full load
d- Same as starting torque
Answer :
337.Alternator compounding characteristics are obtained by
a- Keeping Vt constant
b- Keepping Eg comstant
c- Varying both Vt and Eg
d- Varying Vt only
Answer :
338.Quardarant switch require for VSI is
a- RCT
b- BJT
c- Diode
d- Ujt
Answer :
339.Turn off snubber is require for
a- SCR
b- Mosfet
c- GTO
d- Traic
Answer :
340.What is the value of A in duplex wave winding
a- 2
b- 4
c- 6
d- 8
Answer :
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341.Dynamometer wattmeter uses
a- Pneumatic damping
b- Eddy current damping
c- Fluid friction
d- Electromagnetic
Answer :
342.In DC machine the induced voltage under MNA is
a- 0
b- Maximum
c- Negative
d- Depend on load
Answer :
343.Dc machine windings are always
d- Short pitched
c- Full pitched
b- Fractional
a- Integral
Answer :
344.Compounding is normally not done to
a- Comulative compound
b- Shunt generator
c- Differential
d- None
Answer :
345.Which of following is active transducer
a- LVDT
b- Inductive transducer
c- Thermocouple
d- Capacitive transducer
Answer :
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346.Which configuration produces 180 degree phase shift between input and output
a- CB
b- Darlington
c- CC
d- CC-CB
e- None
Answer :
347.Concept of armature reaction comes in picture when
a- Only one magnetic field
b- Only two magnetic field
c- Independent of magnetic field
d- No limit
Answer :
348.Star connection of transformer is used for
a- High voltage low capacity
b- Low voltage high capacity
c- Low voltage low capacity
d- High voltage high capacity
e- None
Answer :
Q349.In case of 4 poles D.C Generator Provided with a two layer of Lap winding with sixteen coils, the pole pitch will be
A.32
B.16
C.8
D.4
Answer :
EXPLANATION: Since the winding is two layer winding therefore, the total number of conductor 16 × 2 = 32.
Pole pitch of a DC generator is the ratio of the total number of the conductor to the number of poles.
Pole pitch = Number of conductor / Number of poles = 32 / 4 = 8
Therefore number of pole pitch = 8.
350.The ability of a material to remain magnetized after removal of the magnetizing force is known as
A. permeability
B. reluctance
C. hysteresis
D. retentivity
Answer :
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351.For a given wirewound core, an increase in current through the coil
A. reverses the flux lines
B. decreases the flux density
C. increases the flux density
D. causes no change in flux density
Answer :
352.Electromagnetic induction is the force that produces a magnetic field.
A. True
B. False
Answer :
353.An electromagnetic field exists only when there is
A. an increasing current
B. decreasing current
C. voltage
D. current
Answer :
354.The unit for permeability is
A. Wb/At × m
B. At/m
C. At/Wb
D. Wb
Answer :
355.When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
A. increases
B. decreases
C. remains constant
D. reaches zero
Answer :
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356.If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
A. increases
B. decreases
C. is zero
D. will remain constant
Answer :
357.When the current through the coil of an electromagnet reverses, the
A. direction of the magnetic field reverses
B. direction of the magnetic field remains unchanged
C. magnetic field expands
D. magnetic field collapses
Answer :
358.A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.
A. True
B. False
Answer :
359.Lenz's law defines the polarity of the induced voltage.
A. True
B. False
Answer :
360.Ampere-turn is the unit of magnetomotive force (mmf).
A. True
B. False
Answer :
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361.The tesla is the unit of magnetic flux.
A. True
B. False
Answer :
362.If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density
A. increases
B. decreases
C. remains the same
D. doubles
Answer :
363.Reluctance in a magnetic circuit is analogous to current in an electrical circuit.
A. True
B. False
Answer :
364.When a solenoid is activated, the force that moves the plunger is
A. an electromagnetic field
B. a permanent magnetic field
C. varying voltage
D. a steady current
Answer :
365.When the north poles of two bar magnets are brought close together, there will be
A. no force
B. a downward force
C. a force of attraction
D. a force of repulsion
Answer :
366.Materials with a low retentivity do not retain a magnetic field very well.
A. True
B. False
Answer :
367.magnetic field is made up of flux lines.
A. True
B. False
Answer :
368.The direction of a magnetic field within a magnet is
A. from south to north
B. from north to south
C. back to front
D. front to back
Answer :
369.Hysteresis is the number of lines of force per unit area in a magnetic field.
A. True
B. False
Answer :
370.If a conductor is moved back and forth at a constant rate in a constant magnetic field, the voltage in the conductor will reverse polarity.
A. True
B. False
Answer :
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371.The unit for reluctance is
A. tesla
B. At/Wb
C. At/m
D. Wb
Answer :
372.If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
A. remains unchanged
B. reverses polarity
C. increases
D. decreases
Answer :
373.The induced voltage across a stationary conductor in a stationary magnetic field is
A. zero
B. reversed in polarity
C. increased
D. decreased
Answer :
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The amplitude or peak value or maximum value of an alternating voltage is given by the coefficient of the
- Cosine of the time angle
- Sine of the time angle
- Cotangent of the time angle
- Tangent of the time angle
A radian is defined as the central angle, for which length of its arc
- Should be less than radius
- None of these
- Should be equal to the radius
- Should be greater than radius
If the voltage increases from zero to peak value and decreases back to zero during one alteration, then the average value must be
- c. Between zero to peak value
- d. None of these
- a. Less than zero
- b. Greater than peak value
The ratio of maximum value to effective value of an alternating quantity is called
- Amplitude factor
- . Crest factor
- All of these
- Peak factor
In half wave rectifiers, diode conducts during
- Only positive half cycle
- Both positive and negative half cycle
- Neither in positive half cycle nor in negative half cycle
- Only negative half cycle
Commutator motors have
- Absolutely uniform torque
- Approximately uniform torque
- Non - uniform torque
- None of these
In gravity control, at the zero position of the pointer the controlling torque is
- 0.5
- 7
- Zero
- One
The voltage of the earthed appliance when it is higher and when it is lower than the earth potential will
- Increase to zero, increase to zero
- Fall to zero, increase to zero
- Increase to zero, fall to zeroIncrease to zero, fall to zero
- Fall to zero, fall to zero
Permanent magnet are manufactured by
- Cobalt and nickel
- Iron and cobalt
- Copper sulphate
- ALNICO
For a two - way position control of lamp, the number of switches required is
- d. Four
- a. One
- c. Three
- b. Two
The springs should be
- Sufficient cross-sectional area
- . All of these
- Free from mechanical stress
- They should have a small resistance
Three - phase induction motor is more suitable than single - phase because
- It is self starting
- Better efficiency compared to single - phase
- All of these
- Better power factor compared to single - phase
The most common waveforms of ac is
- Square
- Triangular
- Sinusoidal
- Saw tooth
Electric field intensity is
- Directly proportional to the permittivity
- Inversely proportional to the charge
- Inversely proportional to the force applied
- Directly proportional to the force applied
Necessity of earthing is to
- Protect the human being from shock
- Maintain the line voltage
- All of these
- Protect tall building
In a 3 - phase star connected balanced induction motor, the line voltage is equal to the
- 3 times the phase voltage
- 1/√3 times the phase voltage
- 1/3 times the phase voltage
- √3 times the phase voltage
he number of instantaneous values between zero and the peak value is
- Infinity
- Zero
- Eleven
- One
According to the coulomb’s law, the force between two point charges is
- All of these
- Directly proportional to the product of the charges
- Along the line joining them
- Inversely proportional to the square of the distance between them
ne electron charge is equal to
- 1.925 x 10^–31C
- – 1.6019 x 10^–19C
- 1.6019 x 10^-19C
- – 1.925 x 10^–31C
The undue deterioration in wiring due to the action of dampness, fumes, weather etc is
- Appearance
- Earthing
- Mechanical immunity
- Permanence
One coulomb of charge is equal to the charge of
- 6.242 x 10^18 electrons
- 1.095 x 10 ^–19 electrons
- 1.625 x 10^–31 electrons
- 6.025 x 10^–19 electrons
In Fleming’s right hand rule, the direction of the induced emf in the conductor is given by
- d. None of these
- b. Middle figure
- a. Index figure
- c. Thumb
The two alternating quantities could be added by constructing
- Rhombus
- Parallelograms
- Trapeziums
- Squares
Reluctance in a magnetic material is a property by virtue of which it opposes the creation of
- Magnetic flux
- Electric field density
- Electric flux
- Electric lines of force
Electrical appliances which works on the electromagnetic principle is / are
- Motors
- Generators
- All of these
- Transformers
In a star connected system, the current flowing through the line is
- Lesser than the phase current
- Greater than the phase current
- Equal to the phase current
- None of these
Peak to peak value of a sine wave is
- Equal to the maximum or phase value of sine wave
- Half of the maximum or phase value of sine wave
- Four times the maximum or phase value of sine wave
- Twice the maximum or phase value of sine wave
The equation for electric flux density is given by
- D = εV
- D = ε/V
- D = ε/E
- D = εE
The most effective earth plate is
- Cast - iron plates
- Copper plates
- All of these
- Galvanized iron plates
When windings of 3 - phase induction motor is rotated in a magnetic field, then the emf induced in each phase are of
- Same magnitude but different frequency
- Different magnitude and different frequency
- Same magnitude and same frequency
- Different magnitude but same frequency
In a self excited generator, if the series field opposes the shunt field, then the generator is
- Cumulatively compounded
- Series generator
- Differentially compounded
- None of these
The materials with permeability less than unity are called
- Ferromagnetic materials
- Paramagnetic materials
- Anti ferromagnetic materials
- Diamagnetic materials
In any network of wires carrying currents, the algebraic sum of all currents meeting at a point is equal to
- Sum of incoming current
- Zero
- Sum of outgoing current
- Sum of all the currents
Yoke in a dc machine serves the function of
- All of these
- Providing mechanical support to the poles
- Offers a path of low reluctances to the magnetic flux produced by the poles
- Protects the dc machine from harmful atmospheric elements like dust, moisture and gases
Root mean square value of current is equal to
- 1.732 times the maximum value
- Twice the maximum value
- 0.707 times the maximum value
- 1.414 times the maximum value
Which among the following is true about ohm’s law?
- I ∝ V
- V = IR
- All of these
- I = V/R
Tangent galvanometer can be used to measure
- Current
- Voltage
- Power
- . All of these
The magnetic materials which are strongly attracted by the magnet is
- b. Paramagnetic materials
- d. Anti ferromagnetic materials
- c. Ferromagnetic materials
- a. Diamagnetic materials
Wattmeter is a / an
- Indicating instrument
- All of these
- Recording instrument
- . Integrating instrument
The terminal voltage in the separately excited generators is given by
- V = Eg – Ia Ra
- V = Eg + Ia Ra
- V = Eg - Ia Ra - If Ra
- V = Eg + Ia Ra - If Ra
The magnetic effect is used in
- Electrostatic ammeters and voltmeters
- Moving iron repulsion type instrument
- All of these
- Moving iron attraction type instrument
The bridge used to measure the dielectric loss of an insulator is
- Anderson bridge
- Wein’s bridge
- Schering bridge
- Any of the above
Which of the following instrument can be used in ac bridges for less frequencies upto 200 Hz only?
- Headphone
- Tunable amplifier detector
- Vibration galvanometer
- All of the above
Maxwell bridge is used to measure
- Resistance
- Inductance
- Capacitance
- Frequency
A 100 V Voltmeter has an accuracy of 5% on the full scale. The percentage error while measuring 50 V will be
- 2.5%
- 5%
- 7.5%
- 10%
Least expensive instrument for dc measurements is
- Hot wire instrument
- Dynamometer type moving coil instrument
- Attraction type moving instrument
- Electrostatic type instrument.
A cadmium sulfide cell is a
- Solar cell
- Dry cell
- Photovoltaic cell
- Photoconductive cell
Some substance generates the voltage when they are subjected to mechanical forces or stress along specific planes. Such substance is known as
- Piezoelectric
- Thermo-electric
- Photo-electric
- Radio-active
Which of the following instrument can be used for the measurement of a temperature above 1500°K?
- Mercury thermometer
- Gas Thermometer
- Thermoelectric pyrometer
- Any of the above
A solar cell is
- Same as a photometer
- Same as a photoemissive cell
- Same as a photoconductive cell
- Same as a photovoltaic cell
A piezometer is used to measure
- Strain in structure
- Very low pressure
- Very high pressure
- Leakage reactance
A load cell is a
- Strain gauge
- Photovoltaic cell
- Thermistor
- Pressure pick up
Which of the following quantities cannot be measured by a load cell?
- Pressure
- Temperature
- Level
- All of the above
In series type ohmmeter, full-scale deflection current indicator is marked
- Zero
- Infinite
- 100 ohm
- 1 Megaohm
For the measure of voltage and current in the ratio frequency range, a suitable instrument is
- Moving iron type
- Moving coil type
- Electrothermic type
- Electrostatic type
Which of the following meters will require the smallest shunt resistance?
- 0-10 mA
- 0-100 mA
- 0-1 mA
- 0-10 A
In shunt type ohmmeter, full-scale deflection current indicator is marked
- Zero
- Infinite
- 100 mΩ
- 100 MΩ
The commonly used material for the thermocouples is
- Chromel copel
- Chromel-alumel
- Platinum-rhodium
- Any of the above
A barometer is an element which
- Senses optical input and delivers thermal output
- Senses thermal input
- Senses electrical input and delivers electrical output
- Senses optical input and delivers electrical output
Which of the following statements is incorrect about the hot wire instruments?
- Their reading is independent of the wave form
- Their response is instantaneous.
- They are unaffected by stray fields
- Their reading is independent of frequency
Which type of damping is generally preferred in case of instruments having a weak magnetic field?
- Air friction damping
- Fluid friction damping
- Eddy current damping
- Hysteresis damping
Voltmeter sensitivity is defined as
- Reciprocal of the full-scale deflection current
- Ohms per volts
- Volts per ohm
- Its degree of sensitiveness to impulse change
Which of the following instrument is undesirable for measurement of AC values?
- Moving iron repulsion type
- Dynamometer type
- The permanent magnet moving coil type
- Moving iron attraction type
In which instrument the deflecting torque depends on the frequency
- Hotwire instrument
- Moving coil instrument
- Moving iron instrument
- Induction type instrument
The braking torque of induction type single-phase energy meter is:-
- Directly proportional to the square of the flux
- Directly proportional to the flux
- Inversely proportional to the flux
- Inversely proportional to the square of the flux
The radiant efficiency of the luminous source depends on
- The shape of the source
- The temperature of the source
- The wavelength of the light rays
- All of the above
Lightwave travel with a velocity of
- 3 × 10^10 cm/s
- 3 × 10^12 cm/s
- 3 × 10^15 cm/s
- 3 × 10^18 cm/s
Carbon arc lamps are commonly used in
- Domestic lighting
- Street lighting
- Cinema Projector
- Photography
Candela is the unit of
- Luminous flux
- Luminous intensity
- Wavelength
- None of the above
The unit of luminous flux is
- Steradian
- Candela
- Lumen
- Lux
The illumination is directly proportional to the cosine of the angle made by the normal to the illuminated surface with the direction of the incident flux. Above statement is associated with
- Planck’s law
- Macbeth’s law of illumination
- Bunsen’s law of illumination
- Lambert’s cosine law
Which of the following will needs the highest level of illumination?
- Proofreading
- Bed Room
- Hospital wards
- Railway platforms
Which of the following will need the lowest level of illumination?
- Displays
- Fine engraving
- Railway platform
- Auditorium
Which of the following lamps gives nearly monochromatic light?
- Sodium vapor lamp
- GLS Lamp
- Tube light
- Mercury vapor lamp
The luminous efficiency of a fluorescent tube is
- 5-10 lumens/watt
- 15-20 lumens/watt
- 30-40 lumens/watt
- 60-65 lumens/watt
One lumen per square meter is the same as
- One lux
- One Candela
- One foot candle
- One lumen meter
The standard wattage of 3ft. fluorescent tube is
- 10 W
- 40 W
- 65 W
- 100 W
For the same wattage which lamp is cheapest?
- Sodium Vapor Lamp
- Mercury Vapor Lamp
- Fluorescent tube
- GLS Lamp
The optical instrument used for the comparison of candle power of different sources are known as
- Candle meters
- Radiometers
- Bunsen meter
- Photometer
Which photometer is used for comparing the light of different colors?
- Bunsen photometer
- Grease spot Photometer
- Lummer Brodhum Photometer
- Guilds Flicker Photometer
Which photometer is used for comparing the light of the same colors?
- Bunsen photometer
- Guilds Flicker Photometer
- Both 1 & 2
- None of the above
The Principle of the Simple photometer is based upon
- Inverse Square Law
- Square Law
- Inverse Law
- Lambert cosine Law
Light is produced in electric discharge lamps by
- Heating effect of current
- Magnetic effect of current
- Ionization in a gas or vapor
- Carbon electrodes
The color of the light given out by a sodium vapor discharge lamp is
- Pink
- Bluish Green
- Yellow
- Blue
Lumen/watt is the unit of
- Light Flux
- Luminous Intensity
- Brightness
- Luminous Efficiency
The S.I unit of Luminance is
- Candela
- Lux
- Candela/m^2
- m^2/candela
Which gas is sometimes used in filament lamps?
- Argon
- Krypton
- Nitrogen
- Carbon dioxide
Which bulb operated on the lowest power?
- Night Bulb
- Neon Bulb
- Torch Bulb
- GLS Bulb
The output of a tungsten filament lamp depends on
- Size of lamp
- Size of shell
- Temperature of filament
- All of the above
A zero watt lamp consumes
- No power
- About 5 to 7 W power
- About 15 to 20 W power
- About 25 to 30 W power
Melting temperature of tungsten is
- 2000° K
- 2500° K
- 2655° K
- 3655° K
The life of the incandescent lamp is expected to be
- 100 Hours
- 200 Hours
- 1000 Hours
- 10000 Hours
The source of illumination for a cinema projector is
- Incandescent Lamp
- Mercury Vapour Lamp
- Carbon Arc lamp
- Sodium Lamp
In the case of frosted GLS lamps, the frosting of the shell is done by
- Ozone
- Ammonia
- Acid etching
- Saltwater
For connecting two generators in parallel, they should have __________________
- a) Same current rating
- b) Same ohmic rating
- c) Same voltage rating
- d) All ratings must be same
While connecting two DC generators in parallel, which of the following is not a desirable condition?
- Same voltage rating
- ) Same percentage voltage regulation
- Same percentage speed regulation of the prime movers
- Same current rating
We connect two generators in parallel _____________
- a) For large DC load
- b) For small DC load
- c) For any DC load
- d) For any AC or DC load
Load sharing of two generators connected in parallel is determined by __________
- a) Internal characteristics
- b) External characteristics
- c) Both internal and external characteristics
- d) It doesn’t depend on load sharing
For a parallel operation of 2 DC shunt generators, we get net external characteristics ___________
- a) Starting from the same no-load point and between generator 1 and generator 2
- b) Starting from the same no-load point and below generator 1 and generator 2
- c) Starting from the same no-load point and above generator 1 and generator 2
- d) Can’t be determined
When two compound generators are connected in parallel, when load current in generator 1 is increased __________
- a) Both generator will share same load
- b) Generator 1 will start running as motor
- c) Generator 2 will be overloaded
- d) Generator 2 will start running as motor
While running two compound motors in parallel, we connect equalizer ring between ________
- a) Two armatures
- b) Two fields
- c) Two load points
- d) Anywhere
When two DC series motors are connected in parallel, the resultant speed is __________
- a) More than the normal speed
- b) Loss than the normal speed
- c) Normal speed
- d) Zero
. The armature of DC generator is laminated to
- 1. Reduce Hysteresis loss
- 2. Insulate the Core
- 3. Reduce eddy current loss
- 4. Provide air cooling passage
. The commutator segments are connected to the armature conductor by means of
- 1. Copper Lugs
- 2. Insulation Pads
- 3. Resistance wires
- 4. Brazing
. In D.C Generators the pole shoes are fastened to the pole core by
- 1. Rivets
- 2. Resistance wire
- 3. Copper Lugs
- 4. Counter sunk screw
. The bearing used to support the rotor shafts are generally
- 1. Ball Bearing
- 2. Magnetic bearing
- 3. Bush bearing
- 4. None of the above
. In Lap winding, the number of brushes is always
- 1. Double the number of poles
- 2. Same as number of poles
- 3. Half the number of poles
- 4. Multiple of number of poles
. In case of wave wound generators, the average pitch is
- 1. Must be Odd
- 2. May be Odd or Even
- 3. Must be Even
- 4. None of the above
. The material for commutator Brushes is generally
- 1. Mica
- 2. Cast Iron
- 3. Copper
- 4. Carbon
. For Generating large current on D.C generators which winding is generally preferred
- 1. Progressive wave winding
- 2. Lap Winding
- 3. Retrogressive Lap winding
- 4. Current depends on design
. The insulating material used for the commutator segment is generally
- 1. Graphite
- 2. Carbon
- 3. Mica
- 4. Insulating varnish
. The purpose of providing dummy coils in a generator is
- 1. To provide mechanical balance for the rotor
- 2. To reduce eddy current loss
- 3. To reduce hysteresis loss
- 4. To increase efficiency of Generator
. In D.C generator the cause of brush wear may be
- 1. Rough Commutator surface
- 2. Imperfect Contacts
- 3. Server Sparking
- 4. Any of the Above
. When the number of poles and number of armature conductor are fixed in D.C generator then which winding will give Higher EMF?
- 1. Lap Winding
- 2. Wave Winding
- 3. Either Lap or Wave Winding
- 4. Depend upon the conductor
. According to Fleming’s Right – Hand Rule for finding the direction of induced emf, When middle finger point in the direction of induced emf forefinger will point in the direction of
- 1. Lines of Force
- 2. Motion of Conductor
- 3. Magnetic Flux Direction
- 4. None of the Above
. Load sharing of two generators connected in parallel is determined by __________
- a) Internal characteristics
- b) External characteristics
- c) Both internal and external characteristics
- d) It doesn’t depend on load sharing
. For a parallel operation of 2 DC shunt generators, we get net external characteristics
- a) Starting from the same no-load point and between generator 1 and generator 2
- b) Starting from the same no-load point and below generator 1 and generator 2
- c) Starting from the same no-load point and above generator 1 and generator 2
- d) Can’t be determined
. When two compound generators are connected in parallel, when load current in generator 1 is increased __________
- a) Both generator will share same load
- b) Generator 1 will start running as motor
- c) Generator 2 will be overloaded
- d) Generator 2 will start running as motor
. While running two compound motors in parallel, we connect equalizer ring between ___________
- a) Two armatures
- b) Two fields
- c) Two load points
- d) Anywhere
. In liquid level and electrical system analogy, voltage is considered analogous to
- (c) liquid flow rate
- (d) none of the above
- (b) liquid flow
- (a) head
The on-off controller is a _____ system.
- linear
- discontinuous
- ) digital
- non-linear
In a stable control system backlash can cause which of the following ?
- (d) Low-level oscillations
- (b) Overdamping
- (c) Poor stability at reduced values of open loop gain
- (a) Underdamping
increases the steady state accuracy.
- (a) Integrator
- (b) Differentiator
- (d) Phase lag compensator
- (c) Phase lead compensator
. A.C. servomotor resembles
- (c) direct current series motor
- (c) direct current series motor
- (d) universal motor
- (a) two phase induction motor
The second derivative input signals modify which of the following ?
- ) The gain of the system
- The time constant of the system
- ) The time constant and suppress the oscillations
- Damping of the system
- None of the above
is an open loop control system.
- (b) Field controlled D.C. motor
- (d) Metadyne
- (a) Ward Leonard control
- (c) Stroboscope
. Regenerative feedback implies feedback with
- (d) positive sign
- (a) oscillations
- (c) negative sign
- (b) step input
Zero initial condition for a system means
- zero stored energy
- input reference signal is zero
- ) ne initial movement of moving parts
- ) system is at rest and no energy is stored in any of its components
The band width, in a feedback amplifier.
- (a) remains unaffected
- (b) decreases by the same amount as the gain increase
- (c) increases by the same smount as the gain decrease
- (d) decreases by the same amount as the gain decrease
The capacitance, in force-current analogy, is analogous to
- momentum
- ) velocity
- ) mass
- displacement
Due to which of the following reasons excessive bond width in control systems should be avoided ?
- None of the above
- It leads to low relative stability
- It leads to slow speed of response
- Noise is proportional to band width
Transfer function of a system is used to calculate which of the following ?
- ) The steady state gain
- The time constant
- The output for any given input
- The order of the system
In electrical-pneumatic system analogy the current is considered analogous to
- (b) pressure
- (c) air flow
- (d) air flow rate
- (a) velocity
Which of the following statements is correct for any closed loop system ?
- None of the above
- All the co-efficients are always non-zero
- Only one of the static error co-efficients has a finite non-zero value
- All the co-efficients can have zero value
Which of the following statements is correct for a system with gain margin close to unity or a phase
margin close to zero ?
- The system is highly oscillatory
- The system is highly stable
- ) None of the above
- ) The system is relatively stable
In a control system the output of the controller is given to
- (a) final control element
- (b) amplifier
- (e) none of the above
- (d) sensor
- (c) comparator
The transient response, with feedback system,
- (d) decays quickly
- (b) rises quickly
- (a) rises slowly
- (c) decays slowly
Which of the following is the input to a controller ?
- (d) Sensed signal
- (a) Servo signal
- (c) Error signal
- b) Desired variable value
On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend ?
- b) Loop gain
- (a) Frequency
- c) Forward gain
- (d) All of the above
The temperature, under thermal and electrical system analogy, is considered analogous to
- capacitance
- none of the above
- ) current
- voltage
In force-voltage analogy, velocity is analogous to
- (d) capacitance
- (b) charge
- (c) inductance
- (a) current
In an automatic control system which of the following elements is not used ?
- (d) Oscillator
- (c) Sensor
- (b) Final control element
- (a) Error detector
Mass, in force-voltage analogy, is analogous to
- (a) charge
- (d) resistance
- (c) inductance
- (b) current
In thermal-electrical analogy charge is considered analogous to
- (c) reciprocal of temperature
- (b) reciprocal of heat flow
- (e) none of the above
- (a) heat flow
- (d) temperature
As a result of introduction of negative feedback which of the following will not decrease ?
- a) Band width
- (d) Instability
- (c) Distortion
- (b) Overall gain
The viscous friction co-efficient, in force-voltage analogy, is analogous to
- (d) reciprocal of conductance
- (e) none of the above
- (b) resistance
- (c) reciprocal of inductance
- (a) charge
The output of a feedback control system must be a function of
- (e) input and feedback signal
- (d) output and feedback signal
- (a) reference and output
- (b) reference and input
A control system with excessive noise, is likely to suffer from
- d) oscillations
- (a) saturation in amplifying stages
- (c) vibrations
- (b) loss of gain
A controller, essentially, is a
- (d) amplifier
- (a) sensor
- (b) clipper
- (c) comparator
The a.c. the armature winding of an alternator is
- Star-delta connected
- Generally delta-connected
- Delta star connected
- Always star-connected
Drop-in alternator frequency is corrected by:
- Automatic Voltage Regulator
- Damper Winding
- Decreased Prime Mover Output
- Increased Prime Mover Output
The angular displacement between two interconnected stations is mainly due to
- The reactance of the Interconnector
- Armature reactance of both alternators
- The impedance of the Interconnector
- The reactance of the interconnector
In the case of Zero Power factor leading load on the alternator, the effect of armature reaction is
- To increase Induced EMF
- To cross-Magnetize
- To de-magnetize
- To decrease the induced EMF
In synchronous motor rotor, copper losses are met by
- DC Source
- AC Input
- Supply Mains
- Armature Input
In case of leading power factor, the terminal voltage of the alternator will
- Rise on removing the full load
- Fall on adding the full load
- Rise on adding the full load
- Fall on removing the full load
When any one-phase of a 3-phase synchronous motor is short-circuited, the motor
- Will not come upto speed
- Will refuse to start
- Will overheat in the spot
- Will fail to pull into step
A 10 pole AC generator rotates at 1200 rpm. The frequency of AC voltage in cycles per second will be
- 60
- 100
- 160
- 120
The output frequency of an alternator depends on
- Rotational speed only
- Types of winding
- Number of poles and rotational speed
- Numbers of poles only
The number of electrical degrees passed through in one revolution of a six pole synchronous alternator is
- 3600
- 720
- 1800
- 1000
If the input to the prime mover of an alternator is kept constant but the excitation is changed, then the
- Reactive component of the output is changed
- Active component of output is changed
- Power factor remains constant
- Power factor is reduced
When an alternator is running on no-load the power supplied by the prime mover of an alternator goes to
- Meet Cooper losses and windage losses in an armature
- Produce E.M.F in the armature winding
- Meet no-load losses
- Meet iron losses
The power factor of an alternator depends on
- Core Losses
- Armature losses
- Speed of Motor
- Type of Load
During the failure of prime mover in an alternator which relay is used to restore the working condition
- Differential Relay
- Over speed relay
- Buchholz Relay
- Reverse Power Relay
Pitch factor is the ratio of emf of
- Full pitch coil to short pitch coil
- Concentrated winding to distributed winding
- Full pitch winding to distributed winding
- Short pitch coil to full pitch coil
Synchronizing torque comes into operation under all of the following cases except
- Phase difference between two voltages
- Phase difference between two current
- Frequency difference between two voltages
- Changing excitation current
In an alternator, voltage drops occurs in
- (A) armature resistance only
- (B) armature resistance and leakage reactance
- (C) armature resistance, leakage reactance and armature reaction
- (D) armature resistance, leakage reactance, armature reaction and earth connections.
The magnitude of various voltage drops that occur in an alternator, depends on
- (A) power factor of the load
- (B) load current
- (C) power factor x load current
- (D) power factor x (load current)2.
Which type of rotor is best for a turbo-alternator?
- Salient pole type
- Cylindrical rotor type
- Salient pole & Cylindrical rotor
- Non-salient pole typeNon-salient pole type
If the frequency of an alternator increase then
- Speed will remain constant
- Its speed increases
- Its speed decreases
- None of the are correct
Two alternators A and B are sharing an inductive load equally. If the excitation of alternator A is increased then
- Alternator A will deliver more current
- Alternator B will Deliver more current
- Both Alternator will deliver the same current
- Both alternators will share the load equally
The frequency of an alternator in an aircraft system is
- 400 Hz
- 300 Hz
- 60 Hz
- 200 Hz
Three-phase alternator are invariably star connected because
- The small conductor can be used
- Magnetic Loss is minimized
- Less number of wire turns are used
- Higher terminal voltage is obtained
In an alternator chording angle for a flux, wave is α its value for 7th harmonic is
- 2α
- 5α
- 7α
- 8α
For eliminating the 7th harmonic of emf wave of an alternator the fractional pitch must be
- 3/2
- 7/8
- 6/7
- 2/3
One of the following condition which is not necessary when the alternator is operating in parallel
- Same rating
- Same phase Rotation
- The terminal voltage of both alternators must be the same
- Same frequency
It is never advisable to connect a stationary alternator to live bus bar because of it
- Will Get burn
- Will behave as a synchronous motor
- Will Behave as an induction motor
- Will decrease the bus bar voltage
Zero power factor method is used to find
- Voltage Regulation
- Efficiency
- Armature resistance
- Synchronous Impedance
The load sharing between two steam-driven alternators operating in parallel may be adjusted by varying the
- Power factor
- Power factor
- Steam supply to the prime mover
- Frequency
Active power of an alternator can be varied by
- Increasing field excitation
- Changing prime mover speed
- Decreasing field excitation
- Decreasing Frequency
If the diameter of the conductor is increased
- the inductance is increased
- the inductance is decreased
- the resistance is increased
- no change in inductance and resistance
Due to proximity effect, the increase in conductor resistance is not negligible in
- underground cable
- overhead transmission lines
- communication lines
- all of the above
The fact that current density is higher at the surface when compared to centre is known as
- carona
- proximity effect
- skin effect
- all of the above
The presence of earth in case of overhead lines
- increase inductance
- increase capacitance
- decrease inducatance
- decrease capacitance
The term self GMD is used to calculate
- capacitance
- inductance
- resistance
- both 1 and 2
Inductance of transmission line will decrease when
- both GMD and GMR increase
- both GMD and GMR decrease
- GMD increase and GMR decrease
- GMD decrease and GMR increase
If we increase the spacing between the phase conductors, the line capacitance
- increases
- decreases
- remains unaffected
- none of the above
If we increase the length of the transmission line, the charging current
- increases
- decreases
- remains unaffected
- none of the above
In triangular configuration, inductance and capacitance values are ------ and ------ respectively
A.less, less
B. higher, higher
C. less, higher
D. higher, less
If we increase the spacing between the phase conductors, the value of line inductance
- decrease
- increase
- remains unaffected
- none of the above
Surge impedance loading of a 3-phase, 400 kV transmission line is 400 Ω. The surge impedance loading is
- 200 MW
- 1600 MW
- 800 MW
- 400 MW
For transmission line which one of the following relation is true?
- AD - BC = 0
- AD + BC = 0
- AD - BC = 1
- AD - BC = -1
Condition for maximum voltage regulation
- tanφ = X/R
- tanφ = R/X
- cosφ = X/R
- cosφ = R/X
Condition for zero voltage regulation is
- tanφ = X/R
- tanφ = R/X
- cosφ = X/R
- cosφ = R/X
Zero voltage regulation is possible only for
- lagging power factor
- leading power factor
- unity power factor
- all of the above
Communications lines are treated as
- short transmission lines
- long transmission lines
- medium transmission lines
- any of the above
Installation of capacitors at suitable locations and of optimum size in a distribution system results in
- improved voltage regulation
- reduction in distribution power loss
- reduction of KVA rating of distribution transformers
- all of the above
Ferranti effect occurs under
- full load
- no load
- half load
- any of the above
Counter poise is used for
- reduce losses
- less surge impedance
- more surge impedance
- proper discharging of lighting surges
A transmission line is compensated with shunt capacitance Csh. After shunt compensation surge impedance loading will
- increases
- decreases
- remains unaffected
- none of the above
Reflection coefficient of voltage is Rv
- 2Zs/(Zs + Zl)
- 2Zl/(Zs + Zl)
- (Zs - Zl)/(Zs + Zl)
- (Zl - Zs)/(Zs + Zl)
Pin insulators are used up to
- 11 kV
- 33 kV
- 120 kV
- any voltage level
․ Which of the following decides the insulation level of 400 kV, EHV line?
- lighting voltage
- radio interference
- skin effect
- switching over voltage
Which of the following insulator is practically used for railway crossings?
- pin insulator
- string insulator
- strain insulator
- all of the above
Stock bridge dampers are used to
- increase the sag
- reduce the vibrations at the point of support
- reduce the tension
- all of the above
․ Bonding is done at the both ends of the cable to reduce the
- sheath loss
- copper loss
- iron loss
- none of the above
Bundled conductors are used for EHV transmission lines primarily for reducing the
- corona loss
- copper loss
- voltage drop across the line
- surge impedance of the line
Which of the following statements is true? Corona loss increases with
- decrease in conductor size and decrease in supply frequency
- increase in conductor size and decrease in supply frequency
- decrease in conductor size and increase in supply frequency
- increase in conductor size and increase in supply frequency
Which of the following statements is/are true? Due to corona,
- interference increases
- power loss increases
- charging current increases
- all of the above
․ Which of the following statements is/are true? Corona is reduced by
- increasing the radius of the conductor
- increasing the distance between the conductor
- decreasing the supply frequency
- all of the above
For a given wirewound core, an increase in current through the coil
A. reverses the flux lines
B. decreases the flux density
C. increases the flux density
D. causes no change in flux density
Reluctance in a magnetic circuit is analogous to current in an electrical circuit.
A. True
B. False
Lenz's law defines the polarity of the induced voltage.
A. True
B. False
A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.
A. True
B. False
Electromagnetic induction is the force that produces a magnetic field.
A. True
B. False
The induced voltage across a stationary conductor in a stationary magnetic field is
A. zero
B. reversed in polarity
C. increased
D. decreased
If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
A. remains unchanged
B. reverses polarity
C. increases
D. decreases
The ability of a material to remain magnetized after removal of the magnetizing force is known as
A. permeability
B. reluctance
C. hysteresis
D. retentivity
The direction of a magnetic field within a magnet is
A. from south to north
B. from north to south
C. back to front
D. front to back
When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
A. increases
B. decreases
C. remains constant
D. reaches zero
When the current through the coil of an electromagnet reverses, the
A. direction of the magnetic field reverses
B. direction of the magnetic field remains unchanged
C. magnetic field expands
D. magnetic field collapses
The unit for permeability is
A. Wb/At × m
B. At/m
C. At/Wb
D. Wb
If a conductor is moved back and forth at a constant rate in a constant magnetic field, the voltage in the conductor will reverse polarity.
A. True
B. False
The unit for reluctance is
A. tesla
B. At/Wb
C. At/m
D. Wb
Ampere-turn is the unit of magnetomotive force (mmf).
A. True
B. False
When the north poles of two bar magnets are brought close together, there will be
A. no force
B. a downward force
C. a force of attraction
D. a force of repulsion
If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
A. increases
B. decreases
C. is zero
D. will remain constant
magnetic field is made up of flux lines.
A. True
B. False
The tesla is the unit of magnetic flux.
A. True
B. False
If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density
A. increases
B. decreases
C. remains the same
D. doubles
Materials with a low retentivity do not retain a magnetic field very well.
A. True
B. False
When a solenoid is activated, the force that moves the plunger is
A. an electromagnetic field
B. a permanent magnetic field
C. varying voltage
D. a steady current
Hysteresis is the number of lines of force per unit area in a magnetic field.
A. True
B. False
An electromagnetic field exists only when there is
A. an increasing current
B. decreasing current
C. voltage
D. current
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1. Peak to peak value of a sine wave is
a- Twice the maximum or phase value of sine wave
b- Half of the maximum or phase value of sine wave
c- Four times the maximum or phase value of sine waved
d- Equal to the maximum or phase value of sine wave
Answer :
2. According to the coulomb’s law, the force between two point charges is
a- Directly proportional to the product of the charges
b- All of these
c- Along the line joining them
d- Inversely proportional to the square of the distance between them
Answer :
3. The most common waveforms of ac is
a- Saw tooth
b- Square
c- Triangular
d- Sinusoidal
Answer :
4. The most effective earth plate is
a- Cast - iron plates
b- Galvanized iron plates
c- Copper plates
d- All of these
Answer :
5. Which among the following is true about ohm’s law?
a- V = IR
b- All of these
c- I ∝ V
d- I = V/R
Answer :
PKR ELECTRICAL ENGINEERING
6. an electron charge is equal to
a- – 1.6019 x 10^–19C
b- – 1.925 x 10^–31C
c- 1.925 x 10^–31C
d- 1.6019 x 10^-19C
Answer :
7. he number of instantaneous values between zero and the peak value is
a- Infinity
b- Eleven
c- One
d- Zero
Answer :
8. The equation for electric flux density is given by
a- D = ε/V
b- D = ε/E
c- D = εV
d- D = εE
Answer :
9. In Fleming’s right hand rule, the direction of the induced emf in the conductor is given by
a. Index figure
b. Middle figure
c. Thumbd.
d.None of these
Answer :
10. When windings of 3 - phase induction motor is rotated in a magnetic field, then the emf induced in each phase are of
a- Different magnitude and different frequency
b- Same magnitude but different frequency
c- Different magnitude but same frequency
d- Same magnitude and same frequency
Answer :
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11. The materials with permeability less than unity are called
a- Ferromagnetic materials
b- Anti ferromagnetic materials
c- Paramagnetic materials
d- Diamagnetic materials
Answer :
12. Yoke in a dc machine serves the function of
a- All of these
b- Offers a path of low reluctances to the magnetic flux produced by the poles
c- Protects the dc machine from harmful atmospheric elements like dust, moisture and gases
d- Providing mechanical support to the poles
Answer :
13. For a two - way position control of lamp, the number of switches required is
a- Four
b- One
c- Two
d- Three
Answer :
14. The two alternating quantities could be added by constructing
a- Squares
b- Parallelograms
c- Trapeziums
d- Rhombus
Answer :
15. In a 3 - phase star connected balanced induction motor, the line voltage is equal to the
a- √3 times the phase voltage
b- 1/√3 times the phase voltage
c- 3 times the phase voltage
d- 1/3 times the phase voltage
Answer :
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16. Permanent magnet are manufactured by
a- Iron and cobalt
b- Copper sulphate
c- ALNICO
d- Cobalt and nickel
Answer :
17. A radian is defined as the central angle, for which length of its arc
a- Should be less than radius
b- None of these
c- Should be equal to the radius
d- Should be greater than radius
Answer :
18. Necessity of earthing is to
a- Protect the human being from shock
b- Protect tall building
c- All of these
d- Maintain the line voltage
Answer :
19. Wattmeter is a / an
a- Recording instrument
b- Indicating instrument
c- All of these
d- . Integrating instrument
Answer :
20. The undue deterioration in wiring due to the action of dampness, fumes, weather etc is
a- Appearance
b- Earthing
c- Permanence
d- Mechanical immunity
Answer :
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21. Electrical appliances which works on the electromagnetic principle is / are
a- All of these
b- Generators
c- Transformers
d- Motors
Answer :
22. The amplitude or peak value or maximum value of an alternating voltage is given by the coefficient of the
a- Cotangent of the time angle
b- Tangent of the time angle
c- Sine of the time angle
d- Cosine of the time angle
Answer :
23. The voltage of the earthed appliance when it is higher and when it is lower than the earth potential will
a- Increase to zero, increase to zero
b- Increase to zero, fall to zeroIncrease to zero, fall to zero
c- Fall to zero, fall to zero
d- Fall to zero, increase to zero
Answer :
24. Commutator motors have
a- None of these
b- Approximately uniform torque
c- Non - uniform torque
d- Absolutely uniform torque
Answer :
25. In a star connected system, the current flowing through the line is
a- Equal to the phase current
b- Lesser than the phase current
c- None of these
d- Greater than the phase current
Answer :
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26 The magnetic materials which are strongly attracted by the magnet is
a-Ferromagnetic materials
b-Diamagnetic materials
d-Anti ferromagnetic materials
a-Paramagnetic materials
Answer :
27. The terminal voltage in the separately excited generators is given by
a- V = Eg + Ia Ra - If Ra
b- V = Eg - Ia Ra - If Ra
c- V = Eg – Ia Ra
d- V = Eg + Ia Ra
Answer :
28. One coulomb of charge is equal to the charge of
a- 1.625 x 10^–31 electrons
b- 1.095 x 10 ^–19 electrons
c- 6.242 x 10^18 electrons
d- 6.025 x 10^–19 electrons
Answer :
29. Electric field intensity is
a- Directly proportional to the force applied
b- Inversely proportional to the charge
c- Inversely proportional to the force applied
d- Directly proportional to the permittivity
Answer :
30. Three - phase induction motor is more suitable than single - phase because
a- Better power factor compared to single - phase
b- It is self starting
c- All of these
d- Better efficiency compared to single - phase
Answer :
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31. The springs should be
a- . All of these
b- Free from mechanical stress
c- Sufficient cross-sectional area
d- They should have a small resistance
Answer :
32. In gravity control, at the zero position of the pointer the controlling torque is
a- Zero
b- 0.5
c- 7
d- One
Answer :
33. In a self excited generator, if the series field opposes the shunt field, then the generator is
a- Differentially compounded
b- None of these
c- Cumulatively compounded
d- Series generator
Answer :
34. Root mean square value of current is equal to
a- 0.707 times the maximum value
b- 1.414 times the maximum value
c- 1.732 times the maximum value
d- Twice the maximum value
Answer :
35. If the voltage increases from zero to peak value and decreases back to zero during one alteration, then the average value must be
a- Less than zero
b- Greater than peak value
c- None of these
d- Between zero to peak value
Answer :
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36. The ratio of maximum value to effective value of an alternating quantity is called
a- . Crest factor
b- All of these
c- Peak factor
d- Amplitude factor
Answer :
37. In half wave rectifiers, diode conducts during
a- Only negative half cycle
b- Only positive half cycle
c- Both positive and negative half cycle
d- Neither in positive half cycle nor in negative half cycle
Answer :
38. Reluctance in a magnetic material is a property by virtue of which it opposes the creation of
a- Electric lines of force
b- Magnetic flux
c- Electric flux
d- Electric field density
Answer :
39. The magnetic effect is used in
a- Moving iron attraction type instrument
b- Electrostatic ammeters and voltmeters
c- Moving iron repulsion type instrument
d- All of these
Answer :
40. In any network of wires carrying currents, the algebraic sum of all currents meeting at a point is equal to
a- Sum of all the currents
b- Zero
c- Sum of outgoing current
d- Sum of incoming current
Answer :
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41. Electric pressure is also called
c) voltage
b) power
a) resistance
d) energy
Answer :
42. Out of the following which is an insulating material ?
a-Paper
b-Gold
c-Copper
d-Silver
Answer :
43.Conductance is reciprocal of
(a) resistance
(d) capacitance
(b) inductance
(c) reluctance
Answer :
44. With rise in temperature the resistance of semi-conductors
d) remains constant
a) decreases
b) increases
c) first increases and then decreases
Answer :
45. Out of the following which is not a poor conductor ?
d) Tungsten
b) Copper
a) Cast iron
c) Carbon
Answer :
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46.The resistance of a conductor varies inversely as
c) temperature
d) resistivity
a) length
b) area of cross-section
Answer :
47.The substances which have a large number of free electrons and offer a low resistance are called a) insulators
d) conductors
b) inductors
c) semi-conductors
Answer :
48.The property of a conductor due to which it passes current is called
(d) inductance
(b) reluctance
(c) conductance
(a) resistance
Answer :
49.The S.I. unit of power is
a) Henry
b) coulomb
c) watt
d) watt-hour
Answer :
50.The resistance of a copper wire 200 m long is 21 Q. If its thickness (diameter) is 0.44 mm, its specific resistance is around (c) 1.6 x 10""8 Q-m
(d) 1.8 x 10"8 Q-m
(b) 1.4 x 10~8 Q-m
(a) 1.2 x 10~8 Q-m
Answer :
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51.With rise in temperature the resistance of pure metals
c) first increases and then decreases
a) increases
b) decreases
d) remains constant
Answer :
52.The hot resistance of the bulb’s filament is higher than
its cold resistance because the temperature co-efficient of
the filament is
a) zero
c) positive
d) positive
b) negative
Answer :
53.When resistance element of a heater fuses and then
we reconnect it after removing a portion of it, the power
of the heater will
c) remain constant
d) none of the above
b) increase
a) decrease
Answer :
54.A field of force can exist only between
a) two molecules
d) two metal particles
c) two atoms
b) two ions
Answer :
55.Heat in a conductor is produced on the passage of
electric current due to
c) impedance
a) reactance
b) capacitance
d) resistance
Answer :
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56.A substance whose molecules consist of dissimilar
atoms is called
d) insulator
b) super-conductoR
a) semi-conductor
c) compound
Answer :
57.When electric current passes through a metallic
conductor, its temperature rises. This is due to
a) collisions between conduction electrons and atoms
d) mutual collisions between conducting electrons
c) mutual collisions between metal atoms
b) the release of conduction electrons from parent atoms
Answer :
58.International ohm is defined in terms of the
resistance of
c) a cube of copper
a) a column of mercury
b) a cube of carbon
d) the unit length of wire
Answer :
59.The insulation on a current carrying conductor is
provided
c) both of above factors
d) none of above factors
b) to prevent shock
a) to prevent leakage of current
Answer :
60.Resistance of a material always decreases if
d) none of the above is correct
c) number of free electrons available become more
B) temperature of material is increased
a) temperature of material is decreased
Answer :
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61.A glass rod when rubbed with silk cloth is charged
because
a) it takes in `proton
d) it gives away positive charge
b) its atoms are removed
c) it gives away electrons
Answer :
62.Which method can be used for absolute measurement
of resistances
d) Wheatstone bridge method
b) Releigh method
a) Lorentz method
c) Ohm’s law method
Answer :
63.Ohm's law is not applicable to
a) vacuum tubes
d) circuits with low current densities
b) carbon resistors
c) high voltage circuits
Answer :
64.Which of the following materials has the least
resistivity ?
d) Copper
a) Zinc
c) Mercury
b) Lead
Answer :
65.Two bulbs of 500 W and 200 W rated at 250 V will
have resistance ratio as
d) 5 : 2
b) 25 : 4
a) 4 : 25
c) 2 : 5
Answer :
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66.Which one of the following does not have negative temperature co-efficient ?
a) Aluminium
b) Paper
c) Rubber
d) Mica
Answer :
67.Varistors are
a- non-linear resistors
b- insulators
c- resistors with zero temperature coefficient
d- carbon resistors
Answer :
68.A glass rod when rubbed with silk cloth is charged
because
d) it gives away positive charged) it gives away positive charge
b) its atoms are removed
a) it takes in proton
c) it gives away electrons
Answer :
69.The rating of a fuse wire is always expressed in
a- kWh
b- ampere-volts
c- amperes
d- ampere-hours
Answer :
70.For which of the following 'ampere second' could be the unit
a) Reluctance
d) Energy
b) Charge
c) Power
Answer :
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71.If the efficiency of a machine is to be high, what
should be low ?
d) Ratio of output to input
a) Input power
b) Losses
c) True component of power
Answer :
72.A 2 ohms resistor having 1 ampere current will dissipate the power of
a) 2 Watts
b) 2 Joules
c) 1 Watt
d) 1 Joule
Answer :
73.When 2 volts e.m.f. is applied across a 1 farad capacitor, it will store the energy of
a) 2 Joules
b) 2 Watts
c) 4 Joules
d) 1 Watt
Answer :
74.Thevenin’s equivalent circuit can be used to calculate the power loss in the original circuit
a) True
b) False
Answer :
75.A 1 H inductance carrying the current of amperes will store the energy of
a) 2 Watts
b) 2 Joules
c) 4 Watts
d) 4 Joules
Answer :
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76.If two winding having self-inductances L1 and L2, and a mutual inductance m are connected in series will opposite, then the total inductance of series combination will be
a) L1 + L2 - 2M
b) L1 + L2 + 2M
c) L1 - L2 + 2M
d) L1 + L2 – M
Answer :
77.The parallel circuit resonance magnifies
a) Current
b) Voltage
c) Power
d) None of the above
Answer :
78.What will be the equivalent capacitance (in mF) of three capacitors connected in a series having the capacitance of 0.04 mF, 0.08 mF, and 0.02 mF respectively?
1. 0.026
2. 0.032
3. 0.065
4. 0.011
Answer :
79. Determine the resistance (in ohms) of a 14 m long circular wire when the diameter and the conductivity of the wire are 0.6 m and 12 mho/meter respectively.
1. 1.79
2. 2.84
3. 3.64
4. 4.17
Answer :
80.What will be the color-coding of a resistor when the resistance of the resistor is 50 + 2% ohms?
1. Green-Black-Brown-Red
2. Green-Black-Black-Brown
3. Yellow-Brown-Black-Red
4. Green-Black-Black-Red
Answer :
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81.How much energy is stored in a 100 mH inductance when a current of 1A is flowing through it?
1. 5.0 J
2. 0.05
3. 0.5 J
4. 0.005 J
Answer :
Explanation
The energy stored in the magnetic field of an inductor can be expressed as
E = 1/2 L I2
where
E = energy stored (joules, J)
L = inductance (henrys, H)
I = current (amps, A)
1/2(100 x 10-3 x 1)
50 x 10-3 J
0.05 J
82.In a pure inductive circuit if the supply frequency is reduced to half the current will?
1. Be four times as high
2. Be doubled
3. Be reduced to half
4. Be reduced to one fourth
Answer :
Explanation
The amplitude of the current in a pure inductive circuit is given by
Im = Vm/ωl
And ω = 2πf
Im = Vm/2πfl
Im ∝ 1/f
Hence, when the frequency is halved, the amplitude of the current is doubled in a pure inductive circuit.
83.A 10 pole 25 Hz alternator is directly coupled to and is driven by 60 Hz synchronous motor then the number of poles in a synchronous motor is?
1. 24 poles
2. 48 poles
3. 12 Poles
4. None of the above
Answer :
Explanation
Number of poles of alternator Pa = 10
F = 25 Hz (alternator)
F = 60 Hz (motor)
Then the number of poles of motor Pm =?
Since synchronous motor is directly coupled hence
Synchronous speed of an alternator = Synchronous speed of the motor
(120 x 25)/10 = (120 x 60)/ Pm
Pm = 24
84. For painful shock what is the range of electric shock current at 50 Hertz?
1. 0-1 mA
2. 3-5 mA
3. 0-3 mA
4. 5- 10 mA
Answer :
Explanation
• The damage caused by electric shock depends on the current flowing through the body — 1 mA can be felt; 5 mA is painful.
• Above 15 mA, a person loses muscle control, and 70 mA can be fatal.”
• The amount of damage done by the electric shock depends not only on the magnitude of the current, but it also on which portions of the body that the electric current is flowing through. The reason for this is that different parts of the body have different resistances, which can lead to an increase in current
85.If the power factor is high, then the consumer maximum demands
1. Increase
2. Decrease
3. Becomes zero
4. Remains Constant
Answer :
Explanation
Kva=kw/cos$
Now considering the above equation, for a given requirement of kW, the value of kVA reduces if we have good power factor.
Let us understand with an example,
Consider a case wherein we need 100 kW as output. Now
Case1: for a power factor of 0.8
We would require 120kva for fulfilling the required demand. (Calculated as per equation is written above)
Case2: power factor of 1 (unity)
Here, the value of kVA required is 100 kVA. Which is less than the previous case. This indicates that the kVA demand decreases if power factor of my equipment increases.
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86.In an induction motor, no-load the slip is generally
a- 5%
b- 4%
c- 2%
d- Less than 1%
Answer :
87.The shaft of an induction motor is made of
a- Stainless steel
b- Cast iron
c- Carbon steel
d- Aluminium
Answer :
88.The efficiency of an induction motor is about
a- 100%
b- 80-90%
c- Less than 50%
d- Less than 50%
Answer :
89.A double squirrel-cage induction motor has
a- Two series winding in the stator
b- Two rotors moving in the opposite direction
c- Two parallel windings in the stator
d- Two parallel winding in Rotor
Answer :
90.Which of the following number specification refers to FET with one gate
a- 2N
b- 3N
c- 3Y
d- 3X
Answer :
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91.MOSFET has input impedence of
a- 100 mega ohm
b- 1 ohm
c- 10 ohm
d- 0 ohm
e- Non of the above
Answer :
92.Which junction is preferred for high input and low output impedance
a- CE
b- CB
c- CC
d- Any of the above
Answer :
93.The operation of JEFT involves
a- Flow of minority carriers
b- Flow of majority carriers
c- Flow of both the carriers
d- None of the above
Answer :
94.A Quiescent state of a transistor implies
a- 0 bias
b- No output
c- No distrotion
d- No input signal
Answer :
95.Which amplifier operates with least distrotion
a- Class A
b- Class B
c- Class C
d- Class D
Answer :
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96.Leakage current in CE confugration is around
a- Few nano amps
b- Few micro amps
c- Few hundred micro amps
d- Few milli amps
Answer :
97.Bjt is a....... Controlled device, where as FET is a...... Controlled device
a- i, v
b- v, i
c- i, i
d- v, v
Answer :
98.Each of two Cascade stages has a voltage gain of 30. The overall gain is
a- 3
b- 9
c- 30
d- 900
Answer :
99.The properties of JEFT resembles
a- Thermonic valves
b- NPN transistor
c- PNP transistor
d- UJT
Answer :
100.Highest operating frequency can be obtained in case of
a- FET
b- JFET
c- BJT
d- MOSFET
Answer :
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101.Which of the following circuits can operate class AB for audio power output
a- Emitter follower
b- Pushpull
c- Cascade
d- Darlington pair
Answer :
102.Circuit breakers usually operate under
1.Transient state of short-circuit current
2.Sub-transient state of short-circuit current
3.The steady state of short-circuit current
4.After D.C. component has ceased
Answer :
103.Arc in a circuit behaves as
A- A capacitive reactance
B- An inductive reactance
C- A resistance increasing with voltage rise across the arc
D- A resistance decreasing with voltage rise across the arc
Answer :
104.Deflection torque can be produced by
a- Gravity control
b- Spring control
c- Air control
d- Magnetically
Answer :
105.3 Resistor of equal value when connected in series with supply have a power loss of 90W and when they are connected in parallel they would have power loss of?
a- 270W
b- 30W
c- 90W
d- 810W
e- None of the above
Answer :
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106.Which of the following statements is correct
Equipotential lines and field lines
a- Are paralle
b- Are anti parallel
c- Are orthogonal
d- Bear no definite relationship
Answer :
107.Where laplace equation valid
a- Only in free space
b- Only in conductors
c- Only in charge free dielectric regions
d- Only in cavities bounded on all sides by conducting walls
Answer :
108.Which of the following is a vector quantity
a- Magnetic potential
b- Susceptibility
c- Magnetic field intensity
d- Magnetic flux density
Answer :
109.An ideal voltage source will charge an ideal capacitor
a- Infinite time
b- Exponentially
c- Instantaneously
d- None of the above
Answer :
110.Who developed the concept of time varying electric field producing a magnetic field
a- Gauss
b- Faraday
c- Hertz
d- Maxwell
Answer :
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111.The magnitude of magnetic field strength H is independent of
a- Current only
b- Distance only
c- Permeability of medium only
d- Both distance and current
Answer :
112.Which of the following quantities consists of S.I. unit as Hertz?
a- Charge
b- Force
c- Frequency
d- Power
Answer :
113.Which one of the following units is a fundamental unit
a- Newton
b- Ampere
c- Watt
d- Joule/sec
Answer :
114.What is the approximate efficiency of a normal thermal power station ?
a) 30-40%
b) 45-55
c) 20-25%
d) 60-70%
Answer :
115.What is the approximate efficiency of a normal thermal power station ?
a) 30-40%
b) 45-55
c) 20-25%
d) 60-70%
Answer :
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116.The advantage of hydro electric power station over thermal power station is
a) The initial cost of hydro electric power station is low
b) The operation cost of hydro electric power station is low
c) Hydro electric power station can supply the power throughout the year
d) Hydro electric station can be constructed at the place where the energy is required
Answer :
117.In which of the following frequency control method tie line may be overloaded
a) Flat frequency control
b) Flat tie line control
c) Parallel frequency
d) All of the above
Answer :
118.Which of the following statements is/are true ?
a) A thermal reactor needs a moderator materiel
b) In nuclear reactor, mltiplication factor is kept almost equal to one
c) Nuclear power plants are used as peak load plants only
d) Both 1 and 2
Answer :
119.Demand factor of a plant is
a) 0
b) 1
c) Less then 1
d) Greater then 1
Answer :
120.The economics of power plant is greatly influenced by
a) Load factor
b) Diversity factor
c) Both 1 and 2
d) Nether 1 nor 2
Answer :
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121.Pelton turbine is a.......turbine
a) Axial flow
b) Inword radial flow
c) Impulsive
d) any of the above
Answer :
122.Which of the following is low specific speed turbine ?
a) Pelton
b) Kaplan
c) Francis
d) Non of the above
Answer :
123.For variable heads of near about but less then 30 meters, which type of turbine is used in hydro power station ?
a) Pelton
b) Kaplan
c) Francis
d) Non of the above
Answer :
124.More efficient plants are used as
a) Base load plant
b) Peak load plant
c) Both 1 and 2
d) Non of the above
Answer :
125.Which of the following statement is/are true regarding infinite line ?
a) It has infinite length
b) It has infinite voltage
c) It maintains the constant voltage
d) Both 2 and 3
Answer :
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126.In thermal power stations, economiser will
a) Increase the thermal efficiency
b Reduce the thermal efficiency
c) Reduce the Heat
d) both 2 and 3
Answer :
127.pulversed coal is
a) Coal free from ash
b) Non smoking coal
c) Coal which bums for long time
d) Coal broken into fine particles
Answer :
128.Which of the following is considered as superior Quality of coal ?
a) Bituminous coal
b) Peat
c) lignite
d) coke
Answer :
129.Which of the following is neglected while analyzing a short transmission line?
a) Power losses
b) Shunt admittances
c) Series impedance
d) None of these
Answer :
130.Following effects are associated with transmission lines
1. Skin effect
2. Corona effect
3. Proximity effect The effective resistance of conductor is increased by
a) 1 only
b) 2 and 3 only
c) 1 and 3 only
d) 1,2 and 3
Answer :
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131.Shunt capacitance is neglected in case of
a) Medium and long transmission lines
b) Long transmission lines
c) Medium transmission lines
d) Short transmission lines
Answer :
132.When a 15 V input pulse with a width equal to two time constants is applied to an RC integrator, the capacitor charges to
A. 15 V
B. 12.9 V
C. 8.6 V
D. 19.45 V
Answer :
133.An inductance of 0.08 H is larger than
A. 0.0000008 H
B. 0.000000008 H
C. 0.000008 H
D. 0.00008 mH
Answer :
134.A 240 H inductor is equivalent to a
a- 0.240 mH inductor
b- 0.000240 mH inductor
c- 240 mH inductor
d- 240 H inductor
Answer :
135.The permeability of a core material is an indication of the ability of the material to establish a magnetic field.
a True
B. False
Answer :
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136.XL is directly proportional to frequency and inductance.
A. True
B. False
Answer :
137.An induced voltage is produced as a result of a dc voltage.
A. True
B. False
Answer :
138.Faraday's law states that relative motion between a magnetic field and a coil induces a voltage across the coil.
A. True
B. False
Answer :
139.Inductance is the property of an inductor that produces an opposition to any change in current.
A. True
B. False
Answer :
140.All coil cores are made of iron.
A. True
B. False
Answer :
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141.Inductance is indirectly proportional to the square of the number of turns, the permeability, and the cross-sectional area of the core.
A. True
B. False
Answer :
142.Some factors that affect the inductance of a coil include:
1. The inductance is proportional to the square of the number of turns;
2. The inductance increases directly as the permeability of the core material increases;
3. The inductance increases directly as the cross-sectional area increases; and
4. The inductance decreases as its length increases.
Answer :
143.Inductors add in parallel.
A. True
B. False
Answer :
144.XC is inversely proportional to frequency and capacitance.
A. True
B. False
Answer :
145.why we subscribe this channel ...,because
a- we want all time mcq on this channel
b- thanks for giving me mcq
c- we are always support to this channel
d- it is helful for competitive exam
Answer :
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146.Voltage leads current by 90° in a capacitor.
A. True
B. False
Answer :
147.The dielectric constant is the ability of a material to establish an electric field.
A. True
B. False
Answer :
148. subscribe electrical engineering channel for all time mcq
a- yes
b- if u subscribe i will provile all time mcq
c- no ..we dont want all time mcq
d- subscribe fast
Answer :
149.Total parallel capacitance is less than that of the smallest capacitor in parallel.
A. True
B. False
Answer :
150.The ohm is the unit of capacitance
A. True
B. False
Answer :
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151.Five time constants are required for a capacitor to charge fully or discharge fully.
a- True
b- False
Answer :
152.Capacitance is directly proportional to plate area and plate separation.
A. True
B. False
Answer :
153.The true power in a capacitor is zero.
A. True
B. False
Answer :
154.A capacitor blocks ac but passes dc.
A. True
B. False
Answer :
155.Energy is stored by a capacitor in a magnetic field.
A. True
B. False
Answer :
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156.When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
a- increases
b- decreases
c- remains constant
d- reaches zero
Answer :
157.Lenz's law defines the polarity of the induced voltage.
A. True
B. False
Answer :
158.A magnetic field is made up of flux lines.
A. True
B. False
Answer :
159.Hysteresis is the number of lines of force per unit area in a magnetic field.
A. True
B. False
Answer :
160.Materials with a low retentivity do not retain a magnetic field very well.
A. True
B. False
Answer :
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161.The formula for finding voltage when resistance and current are known is V = I/R.
A. True
B. False
Answer :
162.The ampere is the unit of resistance.
A. True
B. False
Answer :
163.If an open capacitor is checked with an ohmmeter, the needle will:
A. stay on zero
B. stay on infinity
C. move from zero to infinity
D. move from infinity to zero
Answer :
164.Determine the resistance (in ohms) of a 14 m long circular wire when the diameter and the conductivity of the wire are 0.6 m and 12 mho/meter respectively.
1. 1.79
2. 2.84
3. 3.64
4. 4.17
Answer :
165.Kirchhoff s current law states that
a- net current flow at the junction is positive
b- algebraic sum of the currents meeting at the junction is zero
c- no current can leave the junction without some current entering it
d- total sum of currents meeting at the junction is zero
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166.According to Kirchhoffs voltage law, the algebraic sum of all IR drops and e.m.fs. in any closed loop of a network is always
(a) negative
(b) positive
(c) determined by battery e.m.fs.
(d) zero
Answer :
167.Kirchhoffs current law is applicable to only
a- junction in a network
b- closed loops in a network
c- electric circuits
d- electronic circuits
Answer :
168.A passive network is one which contains
A. Only variable resistance
B. Only some sources of e.m.f. in it
C. Only two sources of e.m.f. in it
D. No source of e.m.f. in it
Answer :
169.A network which contains one or more than one source of e.m.f. is known as
A. Linear network
B. Non-linear network
C. Passive network
D. Active network
Answer :
170.In non-linear network does not satisfy
A. Superposition condition
B. Homogeneity condition
C. Both homogeneity and superposition condition
D. Homogeneity, superposition and associative condition
Answer :
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171.The number of independent equations to solve a network is equal to
A. The number of chords
B. The number of brunches
C. Sum of the number of branches and chords
D. Sum of the number of branches, chords and nodes
Answer :
172.A closed path made by several branches of the network is known as
a- Branch
b- Loop
c- Circuit
d- Junction
Answer :
173.A network has 10 nodes and 17 branches. The number of different node pair voltage would be
A. 7
B. 9
C. 45
D. 10
Answer :
174.Pole of a network is a frequency at which
A. Network function becomes zero
B. Network function becomes infinity
C. Network function becomes unity
D. None of these
Answer :
175. A circuit having neither any energy source nor e.m.f. source is called the .........circuit
A. Unilateral
B. Bilateral
C. Passive
D. Active
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176.Which of the following is an active element in a circuit?
A. Current source
B. Resistance
C. Inductance
D. Capacitance
Answer :
177.Which of the following is not a bilateral element ?
A. Constant current source
B. Resister
C. Inductor
D. capacitor
Answer :
178.The elements which are not capable of delivering energy by its own are known as
a- Unilateral elements
b- Nonlinear elements
c- Passive elements
d- Active elements
Answer :
179.To neglect a voltage source, the terminals across the source are
A. Open-circuited
B. Short-circuited
C. Replaced by some resistance
D. Replaced by inductor
Answer :
180.For determining the polarity of a voltage drop across a resistor, it is necessary to know the
a- Value of resistor
b- Value of current
c- Direction of current flowing through the resistor
d- Value of e.m.f. in the circuit
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181.Which of the following is the passive element ?
A. Capacitance
B. Ideal current source
C. Ideal voltage source
D. All of the above
Answer :
182.Which of the following is not a non-linear element?
A. Gas diode
C. Tunnel diode
B. Heater coil
D. Electric arc
Answer :
183.If the frequency of an alternator increase then
a- Its speed decreases
b- Its speed increases
c- None of the above
d- Speed will remain constant
Answer :
184.In gases the flow of current is due to
a- Electrons only
b- Positive ions only
c- Electrons and positive ions
d- Electrons, positive ions and negative ions
Answer :
185.The minimum requirements for causing flow of current are
a- A voltage source, a resistor and a switch
b- A voltages source and a conductor
c- . A power source and a bulb
d- A voltage source, a conductor an ammeter and a switch
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186.What is switchgear?
a- An apparatus used for switching, controlling and protecting the electrical circuits and equipments
b- It detects the faults only
c- It corrects the faults only.
d- All of above
Answer :
187.A 2 ohms resistor having 1 ampere current will dissipate the power of
a) 2 Watts
b) 2 Joules
c) 1 Watt
d) 1 Joule
Answer :
188.Thevenin’s equivalent circuit can be used to calculate the power loss in the original circuit.
a) True
b) False
Answer :
189.Transient response in the system is basically due to
a) Forces
b) Friction
c) Stored energy
d) Coupling
Answer :
190.Effect of feedback on the plant is to
a) Control system transient response
b) Reduce the sensitivity to plant parameter variations
c) Both (a) and (b)
d) None of these
Answer :
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191.Transfer function of a system is defined as the ratio of output to input in
a) Z-transformer
b) Fourier transform
c) Laplace transform
d) All of these
Answer :
192.Transfer function of a system can used to study its
a) Steady state behavior
b) Transient behavior
c) Both (a) and (b)
d) None of these
Answer :
193.A bridge used for the measurement of capacitance is
d- Wheatstone bridge
a- Wein bridge
b- Maxwell bridge
c- Schering bridge
Answer :
194.The Percentage slip in synchronous motor is
a- 0.01
b- 1
c- 0.005
d- Zero
Answer :
195.Which motor is used in signaling devices ?
a- DC series motor
b- Reluctance motor
c- DC shunt motor
d- Hysteresis motor
Answer :
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196.Brake test for determination of efficiency of a DC machine is ... ?
a- An indirect method
b- A regenerative method
c- A direct method
d- None
Answer :
197.Stepped core is used in transformer in order to reduce?
c - Volume of iron
a- Volume of copper
b- Iron loss
d- Reluctance of core
Answer :
198.Commutation conditions at full load for large DC machines can be efficiently checked by ?
a- Brake test
b- Swinburne's test
c- Hopkinson's test
d- Field test
Answer :
199.Maximum temperature for class F insulation is ?
a- 130°C
b- 120°C
c- 105°C
d- 155°C
Answer :
200.The largest size of steam turbine installed in India is
a- 100 MW
b- 250 Mw
c- 500 MW
d- None of the abobe
Answer :
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201.In Hydro stations, for slow specific speeds that in 4 - 70 RPM range which of the following is turbine is used
a- Pelton
b- Francis
c- Kaplan
d- Propeller
Answer :
202.Rotor used in alternators of hydro electric station is
a- Cylindrical rotor
b- Salient pole rotor
c- Non salient pole rotor
d- Round rotor with ac excitation
Answer :
203.The force between two charges is 120 N. If the distance between the charges is doubled, the force will be
a) 60 N
b) 30 N
c) 40 N
d) 15 N
Answer :
204.The electric field intensity at a point situated 4 meters from a point charge is 200 N/C. If the distance is reduced to 2 meters, the field intensity will be
(a) 400 N/C
(b) 600 N/C
(c) 800 N/C
(c) 800 N/C
Answer :
205.The lines of force due to charged particles are
(a) always straight
(b) always curved
(c) sometimes curved
(d) none of the above
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206.The electric field at a point situated at a distance d from straight charged conductor is
(a) proportional to d
(b) inversely proportional to d
(c) inversely proportional to d
(c) inversely proportional to d
Answer :
207.The direction of electric field due +0 positive charge is .
(a) away from the charge
(b) towards the charge
(c) both (a) and (b)
(d) none of the above
Answer :
208.A field line and an equipotential surface are
(a) always parallel
(b) always at 90°
(c) inclined at any angle 0
(d) none of the above
Answer :
209.The ability of charged bodies to exert force on 6ne another is attributed to the existence of -
(a) electrons
(b) protons
(c) neutrons
(d) electric field
Answer :
210.If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will - (a) decrease
(b) increase
(c) remains unchanged
(d) become zero
Answer :
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211. A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is
(a) 0.024 F
(b) 0.12 F
(c) 0.6 F
(d) 0.8 F
Answer :
212.For making a capacitor, it is better to select a dielectric having
(a) low permittivity
(b) high permittivity
(c) permittivity same as that of air
(d) permittivity slightly more than that of air
Answer :
213.Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air.What will be the value of dielectric constant ?
(a) 50
(b) 100
(c) 150
(d) 200
Answer :
214.In a capacitor the electric charge is stored in -
(a) metal plates
(b) dielectric
(c) both (a) and b)
(d) none of the above
Answer :
215.Which of the following capacitors will have the least variation ?
(a) Paper capacitor
(b) Ceramic capacitor
(c) Silver plated mica capacitor
(d) None of the above
Answer :
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216.The power dissipated in a pure capacitor is
(a) zero
(b) proportional to applied voltage
(c) proportional to value of capacitance
(d) both (b) and (c) above
Answer :
217.In a capacitive circuit
(a) a steady value of applied voltage causes discharge
(b) an increase in applied voltage makes a capacitor charge
(c) decrease in applied voltage makes a capacitor charge
(d) none of the above
Answer :
218.When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between
plates will
(a) remain uncharged
(b) decrease
(c) increase
(d) become zero
Answer :
219.Capacitance increases with
(a) increase in plate area and decrease in distance between the plates
(b) increase in plate area and distance between the plates
(c) decrease in plate area and value of applied voltage
(d) reduction in plate area and distance between the plates
Answer :
220.A capacitor consists of
(a) two insulators separated by a conductor
(b) two conductors separated by an insulator
(c) two insulators only
(d) two conductors only
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221.A paper capacitor is usually available in the form of
(a) tubes
(b) rolled foil
(c) disc
(d) meshed plates
Answer :
222.The unit of capacitance is
(a) henry
(b) ohm
(c) farad
(d) farad/m
Answer :
223.A capacitor in a circuit became hot and ultimately exploded due to wrong connections, which type of capacitor it could be ?
a) Paper capacitor
b) Ceramic capacitor
c) Electrolytic capacitor
d) Any-of the above
Answer :
224.The relative permittivity of free space is given by
(a) 1
(b) 10
(c) 100
(d) 1000
Answer :
225.When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of
(a) 2 joules
(b) 4 joules
(c) 6 joules
(d) 8 joules
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226.Which capacitor will be physically smaller for the same ratings ?
(a) Ceramic capacitor
(b) Paper capacitor
(c) Both will be of equal size
(d) None of the above
Answer :
227.Which of the following material has least value of dielectric constant ?
(a) Ceramics
(b) Oil
(c) Glass
(d) Paper
Answer :
228.Which of the following capacitors can be used for temperature compensation ?
(a) Air capacitor
(b) Ceramic capacitor
(c) Paper capacitor
(d) None of the above
Answer :
229.Paper capacitors usually have a tolerance of
(a) ± 5%
(b) ± 10%
(c) ± 15%
(d) ± 20%
Answer :
230.For closer tolerances which of the following capacitors is usually preferred ?
(a) Paper capacitor
(b) Mica capacitor
(d) None of the above
(c) Ceramic disc capacitor
Answer :
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231.In which of the following reason induction motor operation is stable?
a- Any of two
b- Low slip region
c- High slip region
d- None of the above
Answer :
232.If a transformer is continuously operated the maximum temperature rise will occur in -
(a) core
(b) windings
(c) tank
(d) any of the above
Answer :
233.The hum in a transformer is mainly attributed to
(a) load changes
(b) oil in the transformer
(c) magnetostriction
(d) mechanical vibrations
Answer :
234.The maximum load that a power transformer can carry is limited by its
(a) temperature rise
(b) dielectric strength of oil
(c) voltage ratio
(d) copper loss
Answer :
235.The efficiency of a transformer, under heavy loads, is comparatively low because
(a) copper loss becomes high in proportion to the output
(b) iron loss is increased considerably
(c) voltage drop both in primary and secondary becomes large
(d) secondary output is much less as compared to primary input
Answer :
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236.An open-circuit test on a transformer is conducted primarily to measure
(a) insulation resistance
(b) copper loss
(c) core loss
(d) total loss
(e) efficiency
(f) none of the above
Answer :
237.A no-load test is performed on a transformer to determine - (a) core loss
(b) copper loss
(c) efficiency
(d) magnetising current
(e) magnetising current and loss
Answer :
238.If a transformer is switched on to a voltage more than the rated voltage -
(a) its power factor will deteriorate
(b) its power factor will increase
(c) its power factor will remain unaffected
(d) its power factor will be zero
Answer :
239.Minimum voltage regulation occurs when the power factor of the load is
(a) unity
(b) lagging
(d) zero
(c) leading
Answer :
240.The efficiencies of transformers compared with that of electric motors of the same power are - a . about the same
(a) much smaller
(b) much higher
(c) somewhat smaller
(d) somewhat smaller
Answer :
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241.Off-circuit tap changer is used when transformer is ________________
a) deenergized
b) energized
c) can be used in either energy conditions
d) never used
Answer :
Q242.. The thickness of lamination in D.C machine is approx
a-5 mm
b-0.5 mm
c-0.005 mm
d-5 mm
Answer :
1.According to Faraday’s law of electromagnetic induction rotating armature cuts the magnetic field, due to which an emf is induced in it.2.This emf generate the eddy current which causes eddy current loss.
3.Therefore to reduce the effect of eddy current the armature core is laminated.
4.The thickness of lamination is between 0.1 to 0.5 mm.
Q243.The resistance of armature winding depends upon
a-Length of conductor
b-Cross sectional area of conductor
c-Number of conductors
d-Any of the above
Answer :
explanation:
There are four factors that influence the resistance in a conductor.
⇒Thickness (cross sectional area of the wire). (R ∝ 1/A)
⇒Length ( R ∝ L)
⇒Temperature
⇒Conductivity of material
The number of armature conductor “Z” is constant that depends upon the number of turns on the armature and the type of winding. i.e wave winding or lap winding.
244.Are you satisfied for today's quiz on dc generator
a- 100%
b- 75%
c- 50%
d- 25%
Answer :
245.The resistivity of a conductor depends upon (SSC 2018 -S-1)
a- Pressure
b- Temperature
c- Degree of Illumination
d- Shape of cross-section
Answer :
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246. What will be the equivalent capacitance (in mF) of three capacitors connected in a series having the capacitance of 0.04 mF, 0.08 mF, and 0.02 mF respectively? (SSC 2018 -S-1)
a- 0.026
b- 0.032
c- 0.065
d- 0.011
Answer :
247.If the area, current, and the number of turns of an AC circuit is doubled, then the new inductance will be:-
a- Twice the former
b- Four Times the former
c- Small
d- Half the former
Answer :
248.If the total number of slots in a D.C machine is 25 and the total number of poles is 5, then what is the coil span of the machine?
a- 5
b- 30
c- 20
d- 125
Answer :
249.Calculate the energy efficiency when the input energy is 3000J and output energy is 1000J.
a- 0.5
b- 0.5
c- 0.5
d- 0.333
Answer :
250.The ________ region has the highest area in the transistor
a- Collector
b- Base
c- Base-Emitter
d- Base-Emitter
Answer :
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251.The circuit breaker is a device that is used for protection of circuit. The circuit breaker is an example of:
a- Arresters
b- Conductor
c- Switchgear
d- None of these
Answer :
252.To save energy during braking which type of Braking is used?
a- Regenerative
b- Plugging
c- Dynamic
d- All of these
Answer :
253.For similar carrier and modulating signals, the line current used in CSI is_____________?
A. Identical to line voltage in a VSI
B. Identical to line current in VSI
C. Identical to phase voltage in VSI
D. Identical to phase voltage in CSI
Answer :
254.With rise in temperature the resistance of semi-conductors_________________?
A. decreases
B. increases
C. first increases and then decreases
D. remains constant
Answer :
255.Two resistors are said to be connected in series when___________?
A. same current passes in turn through both
B. both carry the same value of current
C. total current equals the sum of branch currents
D. sum of IR drops equals the applied e.m.f.
Answer :
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256.Which of the following statement is true both for a series and a parallel D. C. circuit?
A. Elements have individual currents
B. Currents are additive
C. Voltages are additive
D. Power are additive
Answer :
257.Which of the following materials has a negative temperature co-efficient of resistance?
A. Copper
B. Aluminium
C. Carbon
D. Brass
Answer :
258.The substances which have a large number of free electrons and offer a low resistance are called____?
A. insulators
B. inductors
C. semi-conductors
D. conductors
Answer :
259.Out of the following which is not a poor conductor__________?
A. Cast iron
B. Copper
C. Carbon
D. Tungsten
Answer :
260.A 3-phase 4 wire system is commonly used on________________?
A. primary transmission
B. secondary transmission
C. primary distribution
D. secondary distribution
Answer :
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261.There is a greater possibility of occurrence of corona during______________?
A. dry weather
B. winter
C. summer heat
D. humid weather
E. none of the above
Answer :
262.Which of the following is not a constituent for making porcelain insulators ?
A. Quartz
B. Kaolin
C. Feldspar
D. Silica
Answer :
263.Which of the following materials is used for overhead transmission lines ?
A. Steel cord aluminium
B. Galvanised steel
C. Cadmium copper
D. Any of the above
Answer :
264.The power transmitted will be maximum when____________?
A. corona losses are minimum
B. reactance is high
C. sending end voltage is more
D. receiving end voltage is more
Answer :
265The steel used in steel cored conductors is usually
A. Alloy steel
B. Stainless steel
C. Mild steel
D. High speed steel
Answer :
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266.. By which of the following systems electric power may be transmitted ?
(a) Overhead system
(b) Underground system
(c) Both (a) and (b)
(d) None of the above
Answer :
267.When a live conductor of public electric supply breaks down and touches the earth which of the
following will happen ?
(a) Current will flow to earth
(b) Supply voltage will drop
(c) Supply voltage will increase
(d) No current will flow in the conductor
(e) None of the above
Answer :
268.When a conductor carries more current on the surface as compared to core, it is due to
(a) permeability variation
(b) corona
(c) skin effect
(d) unsymmetrical fault
(e) none of the above
Answer :
269.The voltage regulation in magnetic amplifier type voltage regulator is effected by
(a) electromagnetic induction
(b) varying the resistance
(c) varying the reactance
(d) variable transformer
Answer :
270.Series capacitors on transmission lines are of little use when the load VAR requirement is
(a) large
(b) small
(b) fluctuating
(d) any of the above
Answer :
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271.The voltage of the single phase supply to residential consumers is
(a) 110 V
(b) 210 V
(c) 230 V
(d) 400 V
Ans:
272.Most of the high voltage transmission lines in India are
(a) underground
(b) overhead
(c) either of the above
(d) none of the above
Answer :
273.The distributors for residential areas are
(a) single phase
(b) three-phase three wire
(c) three-phase four wire
(d) none of the above
Answer :
274.Besides a method of trial and error, which of the following methods is employed for solution of
network problems in interconnected system ?
(a) Circulating current method
(b) Thevenin's theorem
(c) Superposition of currents
(d) Direct application of Kirehhoffs laws
(e) All of the above
Answer :
275.A booster is a
(a) series wound generator
(b) shunt wound generator
(c) synchronous generator
(d) none of the above
Answer :
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276.Which of the following D.C. distribution system is the simplest and lowest in first cost ?
(a) Radial system
(b) Ring system
(c) Inter-connected system
(d) None of the above
Answer :
277.Due to which of the following reasons the cables should not be operated too hot ?
(a) The oil may loose its viscosity and it may start drawing off from higher levels
(b) Expansion of the oil may cause the sheath to burst
(c) Unequal expansion may create voids in the insulation which will lead to ionization
(d) The thermal instability may rise due to the rapid increase of dielectric losses with temperature
(e) All of the above
Answer :
278.The operating voltage of extra high tension cables is upto
(a) 6.6 kV
(b) 11 kV
(c) 33 kV
(d) 66 kV
(e) 132 kV
Answer :
279.The operating voltage of supertension cables is up to
(a) 3.3 kV
(b) 6.6 kV
(c) 11 kV
(d) 33 kV
Answer :
280.The square root of the ratio of line impedance and shunt admittance is called the
a- surge impedance of the line
b- conductance of the line
c- regulation of the line
d- none of the above
Answer :
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281.The ideal load factor should be
a- 1
b- 0.5
d- 0.2
c- 0.8
Answer :
282.The base load power station supplies load ……...in a day
a- 10 hours
b- 16 hours
c- 24 hours
d- 12 hours
Answer :
283.The auto-starters (using three autotransformers) can be used to start cage induction motor of the following type
a- Star and Delta connected
b- None
c- Delta connected only
d- Star connected only
Answer :
284.In a three-phase induction motor, the number of poles in the rotor winding is always
a- Less than the number of poles in the stator
b- Equal to the number of poles in the stator
c- More than the number of poles in the stator
d- Zero
Answer :
285.The shaft of an induction motor must be of
a- Flexible
b- Any of the above
c- Hollow
d- Solid
Answer :
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286.The auto-starters (using three autotransformers) can be used to start cage induction motor of the following type
a- Star and Delta connected
b- None
c- Delta connected only
d- Star connected only
Answer :
287.The size of the synchronous motor decrease with the increase in:-
c- Speed
a- Flux density
b- Horsepower rating
d- All of these
Answer :
288.If the area, current, and the number of turns of an AC circuit is doubled, then the new inductance will be
a- Twice the former
b- Four Times the former
c- Small
d- Half the former
Answer :
289.Iron losses in a D.C. machine are independent of variations in
(a) speed
(b) load
(c) voltage
(d) speed and voltage
Answer :
290.In D.C. generators, current to the external circuit from armature is given through -
(a) commutator
(b) solid connection
(c) slip rings
(d) none of above
Answer :
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291.Brushes of D.C. machines are made of
(a) carbon
(b) soft copper
(c) hard copper
(d) all of above
Answer :
292.Armature reaction of an unsaturated D.C. machine is
(a) crossmagnetising
(b) demagnetising
(c) magnetising
(d) none of above
Answer :
293.The fuse wire is made of
A) nichrome
B) copper
C) lead tin alloy
D) aluminum
Answer :
294.The transformer oil should have _____ Volatility and _____ Viscosity.
a- Low & High
b- High & High
c- Low & Low
d- High & Low
Answer :
295.During open circuit test of a transformer
a- Primary is supplied rated voltage
b- Primary is supplied current at reduce voltage
c- Primary is supplied rated KVA
d- Primary is supplied full load current
Answer :
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296.Which type of winding is used in 3-phase shell type transformer
a- Rectangular Type
b- Cylindrical Type
c- Sandwich Type
d- Circular type
Answer :
297.The transformer laminations are insulated from each other by
a- Mica strip
b- Paper
c- Thin coating of Varnish
d- Any of the above
Answer :
298.Two transformer is connected in parallel. These transformer have different percentage impedance. These is likely to result in
a- Loading in the transformer is not proportional to their KVA rating.
b- Short circuit in secondary
c- Higher copper loss
d- Power factor of one of the transformer is leading while that of the other is lagging.
Answer :
299.Which of the following is the main advantage of auto transformer over a two winding transformer?
a- Reduces hysteresis losses
b- Reduce eddy current losses
c- Copper losses are negligible
d- Saving of copper material
Answer :
300.Which winding of the transformer has less cross section area?
a- Primary winding
b- Secondary Winding
c- High Voltage Winding
d- Low Voltage Winding
Answer :
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301.The core used in high frequency transformer is usually
a- Copper Core
b- Mild Steel Core
c- Air core
d- Iron Core
Answer :
302.Harmonics in transformer result in
a- Increase core losses
b- Increases I2R Losses
c- Interference with communication circuits
d- All of the above
Answer :
303.Stones are provided in the substation to
a- To provide insulation
b- To avoid Fire accident during leakage of transformer oil
c- To avoid growing of plants and weed
d- All of the above
Answer :
304.Cruciform shape is used in transformer core to
a- Reduce core loss
b- Reduce core reluctance
c- Reduce winding copper
d- All of the above
Answer :
305.Which of the following test is performed to determine the leakage reactance
a- Short circuit test
b- Open circuit test
c- Both Open circuit and short circuit test
d- Test by an Impedance bridge
Answer :
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306.During SC test the Power Input to a transformer comprises predominately
a- Core loss
b- Copper loss
c- Hysteresis loss
d- Eddy current loss
Answer :
307.The maximum load that a power transformer can carry is limited by its
a- Voltage ratio
b- Temperature Rise
c- Cooper Loss
d- Dielectric strength of coil
Answer :
308.A shell type transformer has
a- High eddy current losses
b- Reduce magnetic leakage
c- Low hysteresis losses
d- All of the above
Answer :
309.A transformer can have zero voltage regulation closer to zero
a- On full load
b- On overload
c- On leading power factor
d- On zero power factor
Answer :
310.The size of the transformer core mainly depends on
a- Frequency
b- Area of core
c- Flux density of core
d- Both frequency and area of core
Answer :
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311.If we increase the length of the transmission line, the charging current
a- increases
b- decreases
c- remains unaffected
d- none of the above
Answer :
312.Ampere is used to measure
a- Temperature
b- Current
c- Light
d- Weight
Answer :
313.The electric susceptibility of the vacuum is
a- Positive
b- Negative
c- Zero
d- One
Answer :
314.A no-load test is performed on a transformer to determine
d- Magnetizing current only
c- Core losses only
b- Efficiency
a- Magnetizing current and losses
Answer :
315.When two waves of same frequency and same amplitude traveling in opposite directions in a straight line overlap the give rise to:
a- Beats
b- Interference
c- Stationary Wave
d- Harmonics
Answer :
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316.The unit of luminous intensity is
a- Lumen
b- Lux
c- Candela
d- Watt
Answer :
317.For energy sensitive and wide speed control, the preferred control method is
a- Armature control
b- Ward Leonard control
c- Multiple voltage control
d- Field control
Answer :
318.Which of the following materials is used for the permanent magnets?
a- Bras
b- Copper
d- Copper
c- Steel
Answer :
319.Transport of charge carrier in the semiconductor is achieved through
a- Conduction and Diffusion
b- Conduction
c- Diffusion
d- None of these
Answer :
320.Which among the below-mentioned reasons is/are responsible for the occurrence of second breakdown phenomenon is power BJT?
a- Large current
b- Distribution of current in a non-uniform manner
c- Excessive power dissipation
d- All of the above
Answer :
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321.The main function of a transformer is to change
a- Power
b- Frequency
d- Voltage Level
c- Power factor
Answer :
322.Which of the following is a cold cathode lamp?
a- Sodium lamp
b- Neon Lamp
c- CSL Lamp
d- Tubelight
Answer :
323.The V.I characteristics of the diode lie in the
a- 1st and 2nd Quadrant
b- 1st and 3rd Quadrant
c- 1st and 4th Quadrant
d- Only in 1st Quadrant
Answer :
324.Which of the following is used in a semiconductor device?
a- Silicon
b- Graphite
c- Copper
d- Aluminum
Answer :
325.Generator transformer are
a- Step-up transformer
b- Step-down transformer
c- Auto transformer
d- One-one transformer
Answer :
Explanation:-
A step-up transformer associated with the turbine generator systems is called a generator transformer. Its role is to raise the voltage of the electric energy generated which can be efficiently transmitted to the substation via buried cables or overhead lines. Generator transformers step the voltage up from the generator level of typically 10-20 kV to the transmission or sub-transmission voltage.
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326.Two electric bulbs designed to operate with a power of 500 watts in 220-volt line are connected in series with a 110 volt line. The power generated by each bulb will be
a- 31.25 watts
b- 3.125 watts
c- 22 watts
d- 62.5 watts
Answer :
Explanation:-
Given
P = Power = 500 W
Voltage V = 220 volt
Resistance R =
The power is given as
P = V2/R
500 = (220)2/R
R = 96.8 ohms
Now bulb is connected to 110 V supply. Therefore power will be
P = V2/R
P = (110)2/96.8
P = 125 watts
Hence power generated by each bulb as they are connected in series will be
P = 125/2 = 62.5 watts
327.The resistance of an ideal ammeter is
a- Low
b- High
c- Infinite
d- Zero
Answer :
328.Power factor can be improved by connecting which among the following?
a- 1 Static capacitor
b- 2 Resistor
c- 3 Synchronous condenser
d- 4 Both 1 and 3
Answer :
329.Which of the following rotor is used in thermal power plants?
a- Cylindrical rotor
b- Salient pole rotor
d- Either of these
c- Square cage rotor
Answer :
330.In a three-phase induction motor, the number of poles in the rotor winding is always
A. Zero
B. More than the number of poles in stator
C. Less than number of poles in stator
D. Equal to number of poles in stator
Answer:
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331.. In a three-phase induction motor, the number of poles in the rotor
winding is always
(a) zero
(b) more than the number of poles in stator
(c) less than number of poles in stator
(d) equal to number of poles in stator
Answer :
332.In a three-phase induction motor, the number of poles in the rotor winding is always
A. Zero
B. More than the number of poles in stator
C. Less than number of poles in stator
D. Equal to number of poles in stator
Answer :
333.Shunt, series and compound generators are the types of __.
A.Separately excited generators
B.Self-excited generators
C.Long shunt differential compound generators
D.short shunt differential compound generators
Answer :
334.Varistors are -
A) resistor with zero temperature coefficient
B) insulator
C) non linear resistor
D) carbon resistor
Answer :
335.Stator of alternator is identical to
a- Dc machine
b- 3phase induction motor
c- 1 phase induction motor
d- None
Answer :
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336.Maximum torque of induction motor is
a- 2-3 times full load torque
b- 1.5 times full load
c- 7 times full load
d- Same as starting torque
Answer :
337.Alternator compounding characteristics are obtained by
a- Keeping Vt constant
b- Keepping Eg comstant
c- Varying both Vt and Eg
d- Varying Vt only
Answer :
338.Quardarant switch require for VSI is
a- RCT
b- BJT
c- Diode
d- Ujt
Answer :
339.Turn off snubber is require for
a- SCR
b- Mosfet
c- GTO
d- Traic
Answer :
340.What is the value of A in duplex wave winding
a- 2
b- 4
c- 6
d- 8
Answer :
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341.Dynamometer wattmeter uses
a- Pneumatic damping
b- Eddy current damping
c- Fluid friction
d- Electromagnetic
Answer :
342.In DC machine the induced voltage under MNA is
a- 0
b- Maximum
c- Negative
d- Depend on load
Answer :
343.Dc machine windings are always
d- Short pitched
c- Full pitched
b- Fractional
a- Integral
Answer :
344.Compounding is normally not done to
a- Comulative compound
b- Shunt generator
c- Differential
d- None
Answer :
345.Which of following is active transducer
a- LVDT
b- Inductive transducer
c- Thermocouple
d- Capacitive transducer
Answer :
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346.Which configuration produces 180 degree phase shift between input and output
a- CB
b- Darlington
c- CC
d- CC-CB
e- None
Answer :
347.Concept of armature reaction comes in picture when
a- Only one magnetic field
b- Only two magnetic field
c- Independent of magnetic field
d- No limit
Answer :
348.Star connection of transformer is used for
a- High voltage low capacity
b- Low voltage high capacity
c- Low voltage low capacity
d- High voltage high capacity
e- None
Answer :
Q349.In case of 4 poles D.C Generator Provided with a two layer of Lap winding with sixteen coils, the pole pitch will be
A.32
B.16
C.8
D.4
Answer :
EXPLANATION: Since the winding is two layer winding therefore, the total number of conductor 16 × 2 = 32.
Pole pitch of a DC generator is the ratio of the total number of the conductor to the number of poles.
Pole pitch = Number of conductor / Number of poles = 32 / 4 = 8
Therefore number of pole pitch = 8.
350.The ability of a material to remain magnetized after removal of the magnetizing force is known as
A. permeability
B. reluctance
C. hysteresis
D. retentivity
Answer :
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351.For a given wirewound core, an increase in current through the coil
A. reverses the flux lines
B. decreases the flux density
C. increases the flux density
D. causes no change in flux density
Answer :
352.Electromagnetic induction is the force that produces a magnetic field.
A. True
B. False
Answer :
353.An electromagnetic field exists only when there is
A. an increasing current
B. decreasing current
C. voltage
D. current
Answer :
354.The unit for permeability is
A. Wb/At × m
B. At/m
C. At/Wb
D. Wb
Answer :
355.When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
A. increases
B. decreases
C. remains constant
D. reaches zero
Answer :
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356.If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
A. increases
B. decreases
C. is zero
D. will remain constant
Answer :
357.When the current through the coil of an electromagnet reverses, the
A. direction of the magnetic field reverses
B. direction of the magnetic field remains unchanged
C. magnetic field expands
D. magnetic field collapses
Answer :
358.A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.
A. True
B. False
Answer :
359.Lenz's law defines the polarity of the induced voltage.
A. True
B. False
Answer :
360.Ampere-turn is the unit of magnetomotive force (mmf).
A. True
B. False
Answer :
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361.The tesla is the unit of magnetic flux.
A. True
B. False
Answer :
362.If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density
A. increases
B. decreases
C. remains the same
D. doubles
Answer :
363.Reluctance in a magnetic circuit is analogous to current in an electrical circuit.
A. True
B. False
Answer :
364.When a solenoid is activated, the force that moves the plunger is
A. an electromagnetic field
B. a permanent magnetic field
C. varying voltage
D. a steady current
Answer :
365.When the north poles of two bar magnets are brought close together, there will be
A. no force
B. a downward force
C. a force of attraction
D. a force of repulsion
Answer :
366.Materials with a low retentivity do not retain a magnetic field very well.
A. True
B. False
Answer :
367.magnetic field is made up of flux lines.
A. True
B. False
Answer :
368.The direction of a magnetic field within a magnet is
A. from south to north
B. from north to south
C. back to front
D. front to back
Answer :
369.Hysteresis is the number of lines of force per unit area in a magnetic field.
A. True
B. False
Answer :
370.If a conductor is moved back and forth at a constant rate in a constant magnetic field, the voltage in the conductor will reverse polarity.
A. True
B. False
Answer :
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371.The unit for reluctance is
A. tesla
B. At/Wb
C. At/m
D. Wb
Answer :
372.If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
A. remains unchanged
B. reverses polarity
C. increases
D. decreases
Answer :
373.The induced voltage across a stationary conductor in a stationary magnetic field is
A. zero
B. reversed in polarity
C. increased
D. decreased
Answer :
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The amplitude or peak value or maximum value of an alternating voltage is given by the coefficient of the
- Cosine of the time angle
- Sine of the time angle
- Cotangent of the time angle
- Tangent of the time angle
A radian is defined as the central angle, for which length of its arc
- Should be less than radius
- None of these
- Should be equal to the radius
- Should be greater than radius
If the voltage increases from zero to peak value and decreases back to zero during one alteration, then the average value must be
- c. Between zero to peak value
- d. None of these
- a. Less than zero
- b. Greater than peak value
The ratio of maximum value to effective value of an alternating quantity is called
- Amplitude factor
- . Crest factor
- All of these
- Peak factor
In half wave rectifiers, diode conducts during
- Only positive half cycle
- Both positive and negative half cycle
- Neither in positive half cycle nor in negative half cycle
- Only negative half cycle
Commutator motors have
- Absolutely uniform torque
- Approximately uniform torque
- Non - uniform torque
- None of these
In gravity control, at the zero position of the pointer the controlling torque is
- 0.5
- 7
- Zero
- One
The voltage of the earthed appliance when it is higher and when it is lower than the earth potential will
- Increase to zero, increase to zero
- Fall to zero, increase to zero
- Increase to zero, fall to zeroIncrease to zero, fall to zero
- Fall to zero, fall to zero
Permanent magnet are manufactured by
- Cobalt and nickel
- Iron and cobalt
- Copper sulphate
- ALNICO
For a two - way position control of lamp, the number of switches required is
- d. Four
- a. One
- c. Three
- b. Two
The springs should be
- Sufficient cross-sectional area
- . All of these
- Free from mechanical stress
- They should have a small resistance
Three - phase induction motor is more suitable than single - phase because
- It is self starting
- Better efficiency compared to single - phase
- All of these
- Better power factor compared to single - phase
The most common waveforms of ac is
- Square
- Triangular
- Sinusoidal
- Saw tooth
Electric field intensity is
- Directly proportional to the permittivity
- Inversely proportional to the charge
- Inversely proportional to the force applied
- Directly proportional to the force applied
Necessity of earthing is to
- Protect the human being from shock
- Maintain the line voltage
- All of these
- Protect tall building
In a 3 - phase star connected balanced induction motor, the line voltage is equal to the
- 3 times the phase voltage
- 1/√3 times the phase voltage
- 1/3 times the phase voltage
- √3 times the phase voltage
he number of instantaneous values between zero and the peak value is
- Infinity
- Zero
- Eleven
- One
According to the coulomb’s law, the force between two point charges is
- All of these
- Directly proportional to the product of the charges
- Along the line joining them
- Inversely proportional to the square of the distance between them
ne electron charge is equal to
- 1.925 x 10^–31C
- – 1.6019 x 10^–19C
- 1.6019 x 10^-19C
- – 1.925 x 10^–31C
The undue deterioration in wiring due to the action of dampness, fumes, weather etc is
- Appearance
- Earthing
- Mechanical immunity
- Permanence
One coulomb of charge is equal to the charge of
- 6.242 x 10^18 electrons
- 1.095 x 10 ^–19 electrons
- 1.625 x 10^–31 electrons
- 6.025 x 10^–19 electrons
In Fleming’s right hand rule, the direction of the induced emf in the conductor is given by
- d. None of these
- b. Middle figure
- a. Index figure
- c. Thumb
The two alternating quantities could be added by constructing
- Rhombus
- Parallelograms
- Trapeziums
- Squares
Reluctance in a magnetic material is a property by virtue of which it opposes the creation of
- Magnetic flux
- Electric field density
- Electric flux
- Electric lines of force
Electrical appliances which works on the electromagnetic principle is / are
- Motors
- Generators
- All of these
- Transformers
In a star connected system, the current flowing through the line is
- Lesser than the phase current
- Greater than the phase current
- Equal to the phase current
- None of these
Peak to peak value of a sine wave is
- Equal to the maximum or phase value of sine wave
- Half of the maximum or phase value of sine wave
- Four times the maximum or phase value of sine wave
- Twice the maximum or phase value of sine wave
The equation for electric flux density is given by
- D = εV
- D = ε/V
- D = ε/E
- D = εE
The most effective earth plate is
- Cast - iron plates
- Copper plates
- All of these
- Galvanized iron plates
When windings of 3 - phase induction motor is rotated in a magnetic field, then the emf induced in each phase are of
- Same magnitude but different frequency
- Different magnitude and different frequency
- Same magnitude and same frequency
- Different magnitude but same frequency
In a self excited generator, if the series field opposes the shunt field, then the generator is
- Cumulatively compounded
- Series generator
- Differentially compounded
- None of these
The materials with permeability less than unity are called
- Ferromagnetic materials
- Paramagnetic materials
- Anti ferromagnetic materials
- Diamagnetic materials
In any network of wires carrying currents, the algebraic sum of all currents meeting at a point is equal to
- Sum of incoming current
- Zero
- Sum of outgoing current
- Sum of all the currents
Yoke in a dc machine serves the function of
- All of these
- Providing mechanical support to the poles
- Offers a path of low reluctances to the magnetic flux produced by the poles
- Protects the dc machine from harmful atmospheric elements like dust, moisture and gases
Root mean square value of current is equal to
- 1.732 times the maximum value
- Twice the maximum value
- 0.707 times the maximum value
- 1.414 times the maximum value
Which among the following is true about ohm’s law?
- I ∝ V
- V = IR
- All of these
- I = V/R
Tangent galvanometer can be used to measure
- Current
- Voltage
- Power
- . All of these
The magnetic materials which are strongly attracted by the magnet is
- b. Paramagnetic materials
- d. Anti ferromagnetic materials
- c. Ferromagnetic materials
- a. Diamagnetic materials
Wattmeter is a / an
- Indicating instrument
- All of these
- Recording instrument
- . Integrating instrument
The terminal voltage in the separately excited generators is given by
- V = Eg – Ia Ra
- V = Eg + Ia Ra
- V = Eg - Ia Ra - If Ra
- V = Eg + Ia Ra - If Ra
The magnetic effect is used in
- Electrostatic ammeters and voltmeters
- Moving iron repulsion type instrument
- All of these
- Moving iron attraction type instrument
The bridge used to measure the dielectric loss of an insulator is
- Anderson bridge
- Wein’s bridge
- Schering bridge
- Any of the above
Which of the following instrument can be used in ac bridges for less frequencies upto 200 Hz only?
- Headphone
- Tunable amplifier detector
- Vibration galvanometer
- All of the above
Maxwell bridge is used to measure
- Resistance
- Inductance
- Capacitance
- Frequency
A 100 V Voltmeter has an accuracy of 5% on the full scale. The percentage error while measuring 50 V will be
- 2.5%
- 5%
- 7.5%
- 10%
Least expensive instrument for dc measurements is
- Hot wire instrument
- Dynamometer type moving coil instrument
- Attraction type moving instrument
- Electrostatic type instrument.
A cadmium sulfide cell is a
- Solar cell
- Dry cell
- Photovoltaic cell
- Photoconductive cell
Some substance generates the voltage when they are subjected to mechanical forces or stress along specific planes. Such substance is known as
- Piezoelectric
- Thermo-electric
- Photo-electric
- Radio-active
Which of the following instrument can be used for the measurement of a temperature above 1500°K?
- Mercury thermometer
- Gas Thermometer
- Thermoelectric pyrometer
- Any of the above
A solar cell is
- Same as a photometer
- Same as a photoemissive cell
- Same as a photoconductive cell
- Same as a photovoltaic cell
A piezometer is used to measure
- Strain in structure
- Very low pressure
- Very high pressure
- Leakage reactance
A load cell is a
- Strain gauge
- Photovoltaic cell
- Thermistor
- Pressure pick up
Which of the following quantities cannot be measured by a load cell?
- Pressure
- Temperature
- Level
- All of the above
In series type ohmmeter, full-scale deflection current indicator is marked
- Zero
- Infinite
- 100 ohm
- 1 Megaohm
For the measure of voltage and current in the ratio frequency range, a suitable instrument is
- Moving iron type
- Moving coil type
- Electrothermic type
- Electrostatic type
Which of the following meters will require the smallest shunt resistance?
- 0-10 mA
- 0-100 mA
- 0-1 mA
- 0-10 A
In shunt type ohmmeter, full-scale deflection current indicator is marked
- Zero
- Infinite
- 100 mΩ
- 100 MΩ
The commonly used material for the thermocouples is
- Chromel copel
- Chromel-alumel
- Platinum-rhodium
- Any of the above
A barometer is an element which
- Senses optical input and delivers thermal output
- Senses thermal input
- Senses electrical input and delivers electrical output
- Senses optical input and delivers electrical output
Which of the following statements is incorrect about the hot wire instruments?
- Their reading is independent of the wave form
- Their response is instantaneous.
- They are unaffected by stray fields
- Their reading is independent of frequency
Which type of damping is generally preferred in case of instruments having a weak magnetic field?
- Air friction damping
- Fluid friction damping
- Eddy current damping
- Hysteresis damping
Voltmeter sensitivity is defined as
- Reciprocal of the full-scale deflection current
- Ohms per volts
- Volts per ohm
- Its degree of sensitiveness to impulse change
Which of the following instrument is undesirable for measurement of AC values?
- Moving iron repulsion type
- Dynamometer type
- The permanent magnet moving coil type
- Moving iron attraction type
In which instrument the deflecting torque depends on the frequency
- Hotwire instrument
- Moving coil instrument
- Moving iron instrument
- Induction type instrument
The braking torque of induction type single-phase energy meter is:-
- Directly proportional to the square of the flux
- Directly proportional to the flux
- Inversely proportional to the flux
- Inversely proportional to the square of the flux
The radiant efficiency of the luminous source depends on
- The shape of the source
- The temperature of the source
- The wavelength of the light rays
- All of the above
Lightwave travel with a velocity of
- 3 × 10^10 cm/s
- 3 × 10^12 cm/s
- 3 × 10^15 cm/s
- 3 × 10^18 cm/s
Carbon arc lamps are commonly used in
- Domestic lighting
- Street lighting
- Cinema Projector
- Photography
Candela is the unit of
- Luminous flux
- Luminous intensity
- Wavelength
- None of the above
The unit of luminous flux is
- Steradian
- Candela
- Lumen
- Lux
The illumination is directly proportional to the cosine of the angle made by the normal to the illuminated surface with the direction of the incident flux. Above statement is associated with
- Planck’s law
- Macbeth’s law of illumination
- Bunsen’s law of illumination
- Lambert’s cosine law
Which of the following will needs the highest level of illumination?
- Proofreading
- Bed Room
- Hospital wards
- Railway platforms
Which of the following will need the lowest level of illumination?
- Displays
- Fine engraving
- Railway platform
- Auditorium
Which of the following lamps gives nearly monochromatic light?
- Sodium vapor lamp
- GLS Lamp
- Tube light
- Mercury vapor lamp
The luminous efficiency of a fluorescent tube is
- 5-10 lumens/watt
- 15-20 lumens/watt
- 30-40 lumens/watt
- 60-65 lumens/watt
One lumen per square meter is the same as
- One lux
- One Candela
- One foot candle
- One lumen meter
The standard wattage of 3ft. fluorescent tube is
- 10 W
- 40 W
- 65 W
- 100 W
For the same wattage which lamp is cheapest?
- Sodium Vapor Lamp
- Mercury Vapor Lamp
- Fluorescent tube
- GLS Lamp
The optical instrument used for the comparison of candle power of different sources are known as
- Candle meters
- Radiometers
- Bunsen meter
- Photometer
Which photometer is used for comparing the light of different colors?
- Bunsen photometer
- Grease spot Photometer
- Lummer Brodhum Photometer
- Guilds Flicker Photometer
Which photometer is used for comparing the light of the same colors?
- Bunsen photometer
- Guilds Flicker Photometer
- Both 1 & 2
- None of the above
The Principle of the Simple photometer is based upon
- Inverse Square Law
- Square Law
- Inverse Law
- Lambert cosine Law
Light is produced in electric discharge lamps by
- Heating effect of current
- Magnetic effect of current
- Ionization in a gas or vapor
- Carbon electrodes
The color of the light given out by a sodium vapor discharge lamp is
- Pink
- Bluish Green
- Yellow
- Blue
Lumen/watt is the unit of
- Light Flux
- Luminous Intensity
- Brightness
- Luminous Efficiency
The S.I unit of Luminance is
- Candela
- Lux
- Candela/m^2
- m^2/candela
Which gas is sometimes used in filament lamps?
- Argon
- Krypton
- Nitrogen
- Carbon dioxide
Which bulb operated on the lowest power?
- Night Bulb
- Neon Bulb
- Torch Bulb
- GLS Bulb
The output of a tungsten filament lamp depends on
- Size of lamp
- Size of shell
- Temperature of filament
- All of the above
A zero watt lamp consumes
- No power
- About 5 to 7 W power
- About 15 to 20 W power
- About 25 to 30 W power
Melting temperature of tungsten is
- 2000° K
- 2500° K
- 2655° K
- 3655° K
The life of the incandescent lamp is expected to be
- 100 Hours
- 200 Hours
- 1000 Hours
- 10000 Hours
The source of illumination for a cinema projector is
- Incandescent Lamp
- Mercury Vapour Lamp
- Carbon Arc lamp
- Sodium Lamp
In the case of frosted GLS lamps, the frosting of the shell is done by
- Ozone
- Ammonia
- Acid etching
- Saltwater
For connecting two generators in parallel, they should have __________________
- a) Same current rating
- b) Same ohmic rating
- c) Same voltage rating
- d) All ratings must be same
While connecting two DC generators in parallel, which of the following is not a desirable condition?
- Same voltage rating
- ) Same percentage voltage regulation
- Same percentage speed regulation of the prime movers
- Same current rating
We connect two generators in parallel _____________
- a) For large DC load
- b) For small DC load
- c) For any DC load
- d) For any AC or DC load
Load sharing of two generators connected in parallel is determined by __________
- a) Internal characteristics
- b) External characteristics
- c) Both internal and external characteristics
- d) It doesn’t depend on load sharing
For a parallel operation of 2 DC shunt generators, we get net external characteristics ___________
- a) Starting from the same no-load point and between generator 1 and generator 2
- b) Starting from the same no-load point and below generator 1 and generator 2
- c) Starting from the same no-load point and above generator 1 and generator 2
- d) Can’t be determined
When two compound generators are connected in parallel, when load current in generator 1 is increased __________
- a) Both generator will share same load
- b) Generator 1 will start running as motor
- c) Generator 2 will be overloaded
- d) Generator 2 will start running as motor
While running two compound motors in parallel, we connect equalizer ring between ________
- a) Two armatures
- b) Two fields
- c) Two load points
- d) Anywhere
When two DC series motors are connected in parallel, the resultant speed is __________
- a) More than the normal speed
- b) Loss than the normal speed
- c) Normal speed
- d) Zero
. The armature of DC generator is laminated to
- 1. Reduce Hysteresis loss
- 2. Insulate the Core
- 3. Reduce eddy current loss
- 4. Provide air cooling passage
. The commutator segments are connected to the armature conductor by means of
- 1. Copper Lugs
- 2. Insulation Pads
- 3. Resistance wires
- 4. Brazing
. In D.C Generators the pole shoes are fastened to the pole core by
- 1. Rivets
- 2. Resistance wire
- 3. Copper Lugs
- 4. Counter sunk screw
. The bearing used to support the rotor shafts are generally
- 1. Ball Bearing
- 2. Magnetic bearing
- 3. Bush bearing
- 4. None of the above
. In Lap winding, the number of brushes is always
- 1. Double the number of poles
- 2. Same as number of poles
- 3. Half the number of poles
- 4. Multiple of number of poles
. In case of wave wound generators, the average pitch is
- 1. Must be Odd
- 2. May be Odd or Even
- 3. Must be Even
- 4. None of the above
. The material for commutator Brushes is generally
- 1. Mica
- 2. Cast Iron
- 3. Copper
- 4. Carbon
. For Generating large current on D.C generators which winding is generally preferred
- 1. Progressive wave winding
- 2. Lap Winding
- 3. Retrogressive Lap winding
- 4. Current depends on design
. The insulating material used for the commutator segment is generally
- 1. Graphite
- 2. Carbon
- 3. Mica
- 4. Insulating varnish
. The purpose of providing dummy coils in a generator is
- 1. To provide mechanical balance for the rotor
- 2. To reduce eddy current loss
- 3. To reduce hysteresis loss
- 4. To increase efficiency of Generator
. In D.C generator the cause of brush wear may be
- 1. Rough Commutator surface
- 2. Imperfect Contacts
- 3. Server Sparking
- 4. Any of the Above
. When the number of poles and number of armature conductor are fixed in D.C generator then which winding will give Higher EMF?
- 1. Lap Winding
- 2. Wave Winding
- 3. Either Lap or Wave Winding
- 4. Depend upon the conductor
. According to Fleming’s Right – Hand Rule for finding the direction of induced emf, When middle finger point in the direction of induced emf forefinger will point in the direction of
- 1. Lines of Force
- 2. Motion of Conductor
- 3. Magnetic Flux Direction
- 4. None of the Above
. Load sharing of two generators connected in parallel is determined by __________
- a) Internal characteristics
- b) External characteristics
- c) Both internal and external characteristics
- d) It doesn’t depend on load sharing
. For a parallel operation of 2 DC shunt generators, we get net external characteristics
- a) Starting from the same no-load point and between generator 1 and generator 2
- b) Starting from the same no-load point and below generator 1 and generator 2
- c) Starting from the same no-load point and above generator 1 and generator 2
- d) Can’t be determined
. When two compound generators are connected in parallel, when load current in generator 1 is increased __________
- a) Both generator will share same load
- b) Generator 1 will start running as motor
- c) Generator 2 will be overloaded
- d) Generator 2 will start running as motor
. While running two compound motors in parallel, we connect equalizer ring between ___________
- a) Two armatures
- b) Two fields
- c) Two load points
- d) Anywhere
. In liquid level and electrical system analogy, voltage is considered analogous to
- (c) liquid flow rate
- (d) none of the above
- (b) liquid flow
- (a) head
The on-off controller is a _____ system.
- linear
- discontinuous
- ) digital
- non-linear
In a stable control system backlash can cause which of the following ?
- (d) Low-level oscillations
- (b) Overdamping
- (c) Poor stability at reduced values of open loop gain
- (a) Underdamping
increases the steady state accuracy.
- (a) Integrator
- (b) Differentiator
- (d) Phase lag compensator
- (c) Phase lead compensator
. A.C. servomotor resembles
- (c) direct current series motor
- (c) direct current series motor
- (d) universal motor
- (a) two phase induction motor
The second derivative input signals modify which of the following ?
- ) The gain of the system
- The time constant of the system
- ) The time constant and suppress the oscillations
- Damping of the system
- None of the above
is an open loop control system.
- (b) Field controlled D.C. motor
- (d) Metadyne
- (a) Ward Leonard control
- (c) Stroboscope
. Regenerative feedback implies feedback with
- (d) positive sign
- (a) oscillations
- (c) negative sign
- (b) step input
Zero initial condition for a system means
- zero stored energy
- input reference signal is zero
- ) ne initial movement of moving parts
- ) system is at rest and no energy is stored in any of its components
The band width, in a feedback amplifier.
- (a) remains unaffected
- (b) decreases by the same amount as the gain increase
- (c) increases by the same smount as the gain decrease
- (d) decreases by the same amount as the gain decrease
The capacitance, in force-current analogy, is analogous to
- momentum
- ) velocity
- ) mass
- displacement
Due to which of the following reasons excessive bond width in control systems should be avoided ?
- None of the above
- It leads to low relative stability
- It leads to slow speed of response
- Noise is proportional to band width
Transfer function of a system is used to calculate which of the following ?
- ) The steady state gain
- The time constant
- The output for any given input
- The order of the system
In electrical-pneumatic system analogy the current is considered analogous to
- (b) pressure
- (c) air flow
- (d) air flow rate
- (a) velocity
Which of the following statements is correct for any closed loop system ?
- None of the above
- All the co-efficients are always non-zero
- Only one of the static error co-efficients has a finite non-zero value
- All the co-efficients can have zero value
Which of the following statements is correct for a system with gain margin close to unity or a phase
margin close to zero ?
- The system is highly oscillatory
- The system is highly stable
- ) None of the above
- ) The system is relatively stable
In a control system the output of the controller is given to
- (a) final control element
- (b) amplifier
- (e) none of the above
- (d) sensor
- (c) comparator
The transient response, with feedback system,
- (d) decays quickly
- (b) rises quickly
- (a) rises slowly
- (c) decays slowly
Which of the following is the input to a controller ?
- (d) Sensed signal
- (a) Servo signal
- (c) Error signal
- b) Desired variable value
On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend ?
- b) Loop gain
- (a) Frequency
- c) Forward gain
- (d) All of the above
The temperature, under thermal and electrical system analogy, is considered analogous to
- capacitance
- none of the above
- ) current
- voltage
In force-voltage analogy, velocity is analogous to
- (d) capacitance
- (b) charge
- (c) inductance
- (a) current
In an automatic control system which of the following elements is not used ?
- (d) Oscillator
- (c) Sensor
- (b) Final control element
- (a) Error detector
Mass, in force-voltage analogy, is analogous to
- (a) charge
- (d) resistance
- (c) inductance
- (b) current
In thermal-electrical analogy charge is considered analogous to
- (c) reciprocal of temperature
- (b) reciprocal of heat flow
- (e) none of the above
- (a) heat flow
- (d) temperature
As a result of introduction of negative feedback which of the following will not decrease ?
- a) Band width
- (d) Instability
- (c) Distortion
- (b) Overall gain
The viscous friction co-efficient, in force-voltage analogy, is analogous to
- (d) reciprocal of conductance
- (e) none of the above
- (b) resistance
- (c) reciprocal of inductance
- (a) charge
The output of a feedback control system must be a function of
- (e) input and feedback signal
- (d) output and feedback signal
- (a) reference and output
- (b) reference and input
A control system with excessive noise, is likely to suffer from
- d) oscillations
- (a) saturation in amplifying stages
- (c) vibrations
- (b) loss of gain
A controller, essentially, is a
- (d) amplifier
- (a) sensor
- (b) clipper
- (c) comparator
The a.c. the armature winding of an alternator is
- Star-delta connected
- Generally delta-connected
- Delta star connected
- Always star-connected
Drop-in alternator frequency is corrected by:
- Automatic Voltage Regulator
- Damper Winding
- Decreased Prime Mover Output
- Increased Prime Mover Output
The angular displacement between two interconnected stations is mainly due to
- The reactance of the Interconnector
- Armature reactance of both alternators
- The impedance of the Interconnector
- The reactance of the interconnector
In the case of Zero Power factor leading load on the alternator, the effect of armature reaction is
- To increase Induced EMF
- To cross-Magnetize
- To de-magnetize
- To decrease the induced EMF
In synchronous motor rotor, copper losses are met by
- DC Source
- AC Input
- Supply Mains
- Armature Input
In case of leading power factor, the terminal voltage of the alternator will
- Rise on removing the full load
- Fall on adding the full load
- Rise on adding the full load
- Fall on removing the full load
When any one-phase of a 3-phase synchronous motor is short-circuited, the motor
- Will not come upto speed
- Will refuse to start
- Will overheat in the spot
- Will fail to pull into step
A 10 pole AC generator rotates at 1200 rpm. The frequency of AC voltage in cycles per second will be
- 60
- 100
- 160
- 120
The output frequency of an alternator depends on
- Rotational speed only
- Types of winding
- Number of poles and rotational speed
- Numbers of poles only
The number of electrical degrees passed through in one revolution of a six pole synchronous alternator is
- 3600
- 720
- 1800
- 1000
If the input to the prime mover of an alternator is kept constant but the excitation is changed, then the
- Reactive component of the output is changed
- Active component of output is changed
- Power factor remains constant
- Power factor is reduced
When an alternator is running on no-load the power supplied by the prime mover of an alternator goes to
- Meet Cooper losses and windage losses in an armature
- Produce E.M.F in the armature winding
- Meet no-load losses
- Meet iron losses
The power factor of an alternator depends on
- Core Losses
- Armature losses
- Speed of Motor
- Type of Load
During the failure of prime mover in an alternator which relay is used to restore the working condition
- Differential Relay
- Over speed relay
- Buchholz Relay
- Reverse Power Relay
Pitch factor is the ratio of emf of
- Full pitch coil to short pitch coil
- Concentrated winding to distributed winding
- Full pitch winding to distributed winding
- Short pitch coil to full pitch coil
Synchronizing torque comes into operation under all of the following cases except
- Phase difference between two voltages
- Phase difference between two current
- Frequency difference between two voltages
- Changing excitation current
In an alternator, voltage drops occurs in
- (A) armature resistance only
- (B) armature resistance and leakage reactance
- (C) armature resistance, leakage reactance and armature reaction
- (D) armature resistance, leakage reactance, armature reaction and earth connections.
The magnitude of various voltage drops that occur in an alternator, depends on
- (A) power factor of the load
- (B) load current
- (C) power factor x load current
- (D) power factor x (load current)2.
Which type of rotor is best for a turbo-alternator?
- Salient pole type
- Cylindrical rotor type
- Salient pole & Cylindrical rotor
- Non-salient pole typeNon-salient pole type
If the frequency of an alternator increase then
- Speed will remain constant
- Its speed increases
- Its speed decreases
- None of the are correct
Two alternators A and B are sharing an inductive load equally. If the excitation of alternator A is increased then
- Alternator A will deliver more current
- Alternator B will Deliver more current
- Both Alternator will deliver the same current
- Both alternators will share the load equally
The frequency of an alternator in an aircraft system is
- 400 Hz
- 300 Hz
- 60 Hz
- 200 Hz
Three-phase alternator are invariably star connected because
- The small conductor can be used
- Magnetic Loss is minimized
- Less number of wire turns are used
- Higher terminal voltage is obtained
In an alternator chording angle for a flux, wave is α its value for 7th harmonic is
- 2α
- 5α
- 7α
- 8α
For eliminating the 7th harmonic of emf wave of an alternator the fractional pitch must be
- 3/2
- 7/8
- 6/7
- 2/3
One of the following condition which is not necessary when the alternator is operating in parallel
- Same rating
- Same phase Rotation
- The terminal voltage of both alternators must be the same
- Same frequency
It is never advisable to connect a stationary alternator to live bus bar because of it
- Will Get burn
- Will behave as a synchronous motor
- Will Behave as an induction motor
- Will decrease the bus bar voltage
Zero power factor method is used to find
- Voltage Regulation
- Efficiency
- Armature resistance
- Synchronous Impedance
The load sharing between two steam-driven alternators operating in parallel may be adjusted by varying the
- Power factor
- Power factor
- Steam supply to the prime mover
- Frequency
Active power of an alternator can be varied by
- Increasing field excitation
- Changing prime mover speed
- Decreasing field excitation
- Decreasing Frequency
If the diameter of the conductor is increased
- the inductance is increased
- the inductance is decreased
- the resistance is increased
- no change in inductance and resistance
Due to proximity effect, the increase in conductor resistance is not negligible in
- underground cable
- overhead transmission lines
- communication lines
- all of the above
The fact that current density is higher at the surface when compared to centre is known as
- carona
- proximity effect
- skin effect
- all of the above
The presence of earth in case of overhead lines
- increase inductance
- increase capacitance
- decrease inducatance
- decrease capacitance
The term self GMD is used to calculate
- capacitance
- inductance
- resistance
- both 1 and 2
Inductance of transmission line will decrease when
- both GMD and GMR increase
- both GMD and GMR decrease
- GMD increase and GMR decrease
- GMD decrease and GMR increase
If we increase the spacing between the phase conductors, the line capacitance
- increases
- decreases
- remains unaffected
- none of the above
If we increase the length of the transmission line, the charging current
- increases
- decreases
- remains unaffected
- none of the above
In triangular configuration, inductance and capacitance values are ------ and ------ respectively
A.less, less
B. higher, higher
C. less, higher
D. higher, less
If we increase the spacing between the phase conductors, the value of line inductance
- decrease
- increase
- remains unaffected
- none of the above
Surge impedance loading of a 3-phase, 400 kV transmission line is 400 Ω. The surge impedance loading is
- 200 MW
- 1600 MW
- 800 MW
- 400 MW
For transmission line which one of the following relation is true?
- AD - BC = 0
- AD + BC = 0
- AD - BC = 1
- AD - BC = -1
Condition for maximum voltage regulation
- tanφ = X/R
- tanφ = R/X
- cosφ = X/R
- cosφ = R/X
Condition for zero voltage regulation is
- tanφ = X/R
- tanφ = R/X
- cosφ = X/R
- cosφ = R/X
Zero voltage regulation is possible only for
- lagging power factor
- leading power factor
- unity power factor
- all of the above
Communications lines are treated as
- short transmission lines
- long transmission lines
- medium transmission lines
- any of the above
Installation of capacitors at suitable locations and of optimum size in a distribution system results in
- improved voltage regulation
- reduction in distribution power loss
- reduction of KVA rating of distribution transformers
- all of the above
Ferranti effect occurs under
- full load
- no load
- half load
- any of the above
Counter poise is used for
- reduce losses
- less surge impedance
- more surge impedance
- proper discharging of lighting surges
A transmission line is compensated with shunt capacitance Csh. After shunt compensation surge impedance loading will
- increases
- decreases
- remains unaffected
- none of the above
Reflection coefficient of voltage is Rv
- 2Zs/(Zs + Zl)
- 2Zl/(Zs + Zl)
- (Zs - Zl)/(Zs + Zl)
- (Zl - Zs)/(Zs + Zl)
Pin insulators are used up to
- 11 kV
- 33 kV
- 120 kV
- any voltage level
․ Which of the following decides the insulation level of 400 kV, EHV line?
- lighting voltage
- radio interference
- skin effect
- switching over voltage
Which of the following insulator is practically used for railway crossings?
- pin insulator
- string insulator
- strain insulator
- all of the above
Stock bridge dampers are used to
- increase the sag
- reduce the vibrations at the point of support
- reduce the tension
- all of the above
․ Bonding is done at the both ends of the cable to reduce the
- sheath loss
- copper loss
- iron loss
- none of the above
Bundled conductors are used for EHV transmission lines primarily for reducing the
- corona loss
- copper loss
- voltage drop across the line
- surge impedance of the line
Which of the following statements is true? Corona loss increases with
- decrease in conductor size and decrease in supply frequency
- increase in conductor size and decrease in supply frequency
- decrease in conductor size and increase in supply frequency
- increase in conductor size and increase in supply frequency
Which of the following statements is/are true? Due to corona,
- interference increases
- power loss increases
- charging current increases
- all of the above
․ Which of the following statements is/are true? Corona is reduced by
- increasing the radius of the conductor
- increasing the distance between the conductor
- decreasing the supply frequency
- all of the above
For a given wirewound core, an increase in current through the coil
A. reverses the flux lines
B. decreases the flux density
C. increases the flux density
D. causes no change in flux density
Reluctance in a magnetic circuit is analogous to current in an electrical circuit.
A. True
B. False
Lenz's law defines the polarity of the induced voltage.
A. True
B. False
A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.
A. True
B. False
Electromagnetic induction is the force that produces a magnetic field.
A. True
B. False
The induced voltage across a stationary conductor in a stationary magnetic field is
A. zero
B. reversed in polarity
C. increased
D. decreased
If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
A. remains unchanged
B. reverses polarity
C. increases
D. decreases
The ability of a material to remain magnetized after removal of the magnetizing force is known as
A. permeability
B. reluctance
C. hysteresis
D. retentivity
The direction of a magnetic field within a magnet is
A. from south to north
B. from north to south
C. back to front
D. front to back
When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
A. increases
B. decreases
C. remains constant
D. reaches zero
When the current through the coil of an electromagnet reverses, the
A. direction of the magnetic field reverses
B. direction of the magnetic field remains unchanged
C. magnetic field expands
D. magnetic field collapses
The unit for permeability is
A. Wb/At × m
B. At/m
C. At/Wb
D. Wb
If a conductor is moved back and forth at a constant rate in a constant magnetic field, the voltage in the conductor will reverse polarity.
A. True
B. False
The unit for reluctance is
A. tesla
B. At/Wb
C. At/m
D. Wb
Ampere-turn is the unit of magnetomotive force (mmf).
A. True
B. False
When the north poles of two bar magnets are brought close together, there will be
A. no force
B. a downward force
C. a force of attraction
D. a force of repulsion
If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
A. increases
B. decreases
C. is zero
D. will remain constant
magnetic field is made up of flux lines.
A. True
B. False
The tesla is the unit of magnetic flux.
A. True
B. False
If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density
A. increases
B. decreases
C. remains the same
D. doubles
Materials with a low retentivity do not retain a magnetic field very well.
A. True
B. False
When a solenoid is activated, the force that moves the plunger is
A. an electromagnetic field
B. a permanent magnetic field
C. varying voltage
D. a steady current
Hysteresis is the number of lines of force per unit area in a magnetic field.
A. True
B. False
An electromagnetic field exists only when there is
A. an increasing current
B. decreasing current
C. voltage
D. current
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