PKR ELECTRICAL ENGINEERING
Q.1 Materials which can store electrical energy are called
(A) magnetic materials. (B) semi conductors.
(C) dielectric materials. (D) super conductors.
Ans: C
Q.2 ACSR (Aluminium Conductor Steel Reinforced) are used as
(A) over head transmission lines. (B) super conductors.
(C) fuse (D) underground cables.
Ans: A
Q.3 Brass is an alloy of
(A) copper and zinc. (B) copper and iron.
(C) copper and Aluminium. (D) copper and tin.
Ans: A
Q.4 Property of material which allows it to be drawn out into wires is
(A) Ductility. (B) Solder ability.
(C) Super conductivity. (D) Malleability.
Ans: A
Q.5 In n type semi conductor added impurity is
(A) pentavalent. (B) divalent.
(C) tetravalent. (D) trivalent.
Ans: A
Q.6 The covers of electrical machines are made of
(A) soft magnetic materials. (B) hard magnetic materials.
(C) super conductors. (D) semiconductors.
Ans: A
Q.7 The dielectric constant of air is practically taken as
(A) more than unity. (B) unity.
(C) less than unity. (D) zero.
Ans: B
Q.8 n-type semiconductor is an example of
(A) extrinsic semiconductor. (B) intrinsic semiconductor.
(C) super conductor. (D) insulators..
Ans: A
Q.9 Atomic weight of an atom is
(A) sum of the number of protons and neutrons.
(B) sum of the number of protons and electrons.
(C) sum of the number of electrons and neutrons.
(D) sum of the number of electrons, protons and neutrons.
Ans: A
Q.10 Gold and silver are
(A) dielectric materials
(B) low resistivity conducting materials.
(C) magnetic materials.
(D) insulating materials.
Ans: B
Q.11 Phenol and Formaldehyde are polymerised to a resultant product known as
(A) PVC.
(C) polyester.
(B) bakelite.
(D) teflon.
Ans: B
Q.12 Dielectric materials are
(A) Insulating materials.
(B) Semiconducting materials.
(C) Magnetic materials. (D) Ferroelectric materials.
Ans: A
Q.13 Thermocouples are used for the measurement of
(A) humidity. (B) pressure.
(C) temperature. (D) density.
Ans: C
Q.14 Large scale integration chips have between
(A) Less than 10 components. (B) 10 and 100 components.
(C) 100 and 1000 components. (D) More than 1000 components.
Ans: C
Q.15 All semiconductors in their last orbit have
(A) 8 electrons. (B) 2 electrons.
(C) 4 electrons. (D) 6 electrons.
Ans: C
Q.16 The material with lowest resistivity is
(A) constantan. (B) silver.
(C) manganin. (D) nichrome.
Ans: B
Q.17 The property due to which the resistance of some metal or compound vanishes under certain
conditions is
(A) Semi conductivity. (B) Super conductivity.
(C) Curie point. (D) Magnetostriction.
Ans: B
Q.18 Bronze is an alloy of
(A) copper. (B) aluminium.
(C) silver. (D) carbon.
Ans: A
Q.19 Ceramics are good
(A) insulators. (B) conductors.
(C) superconductors. (D) semiconductors.
Ans: A
Q.20 The critical temperature above which the ferromagnetic materials loose their magnetic
property is known as
(A) hysterisis. (B) Curie point.
(C) transition temperature. (D) standard temperature.
Ans: B
Q.21 Permanent magnets are made of
(A) soft magnetic materials. (B) hard magnetic materials.
(C) semi conductors. (D) super conductors.
Ans: B
Q.22 Holes are majority carriers in
(A) P-type semiconductors. (B) N-type semiconductors.
(C) Insulators. (D) Superconductors.
Ans: A
Q.23 Materials, which provide a path to the magnetic flux, are classified as
(A) insulating materials.
(C) magnetic materials.
(B) semi conducting materials.
(D) dielectric materials.
Ans: C
Q.24 Germanium possesses
(A) one valence electrons.
(B) two valence electrons.
(C) three valence electrons. (D) four valence electrons.
Ans: D
Q.25 Dielectric constant of vacuum is
(A) infinity.
(B) 100.
(C) one. (D) zero.
Ans: C
Q.26 Ferrites are
(A) ferromagnetic material.
(B) ferrimagnetic materials.
(C) anti ferromagnetic material. (D) diamagnetic materials.
Ans: A
Q.27 The relative permeability of a paramagnetic substance is
(A) unity. (B) slightly more than unity.
(C) zero. (D) less than unity.
Ans: B
Q.28 Hall effect may be used for which of the following?
(A) determining whether the semiconductor is p or n type.
(B) determining the carrier concentration.
(C) calculating the mobility.
PKR ELECTRICAL ENGINEERING
(D) All the above.
Ans: D Determining whether the semiconductor is p or n type, determining the carrier
concentration, calculating the mobility.
Q.29 Manganin is an alloy of
(A) copper, manganese and nickel. (B) copper and manganese.
(C) manganese and nickel. (D) manganese, aluminium and nickel.
Ans: A
Q.30 Eddy current loss is proportional to the
(A) frequency. (B) square of the frequency.
(C) cube of the frequency. (D) square-root of the frequency.
Ans: B
Q.31 A pure semiconductor under ordinary conditions behaves like
(A) a conductor. (B) an insulator.
(C) a magnetic material. (D) a ferro-electric material.
Ans: B
Q.32 In p-type semiconductor the majority carriers are
(A) holes.
(C) positive ions.
(B) electrons.
(D) negative ions.
Ans: A
Q.33 Copper is completely miscible with
(A) nickel.
(B) gold.
(C) hydrogen. (D) lead.
Ans: B
Q.34 For germanium the forbidden gap is
(A) 0.15ev.
(B) 0.25ev.
(C) 0.5ev. (D) 0.7ev.
Ans: D
Q.35 The dielectric strength of transformer oil should be
(A) 100 V. (B) 5 KV.
(C) 30 KV. (D) 132 KV.
Ans: C
Q.36 Resistivity of conductors is most affected by
(A) composition. (B) temperature.
(C) pressure. (D) current.
Ans: B
Q.37 Copper constantan is used for measuring temperature upto
(A)1400 (B) 750
(C) 400 (D)1100
Ans: C
Q.38 Mica is a
(A) Dielectric material. (B) Insulating material.
(C) Magnetic material. (D) Both insulating and dielectric
material.
Ans: D
Q.39 The conductivity of copper is less than that of silver by
(A) 5 – 10 %. (B) 50 – 60 %.
(C) 80 – 90 %. (D) 20 – 30 %.
Ans: A
Q.40 A ferrite core has less eddy current loss than an iron core because ferrites have
(A) High resistance.
(C) Low permeability.
(B) Low resistance.
(D) High hysteresis.
Ans: A
Q.41 Transformer cores are laminated with
(A) Low carbon steel.
(B) Silicon sheet steel.
(C) Nickel alloy steel. (D) Chromium sheet steel.
Ans: B
Q.42 For silicon the forbidden gap is
(A) 1.1ev.
(B) 0.25ev.
(C) 0.5ev. (D) 0.7ev.
Ans: A
Q.43 Plastics are
(A) Good conductors of heat.
(B) Good conductors of electricity.
(C) Bad conductors of electricity. (D) High density.
Ans: C
Q.44 In order to obtain p-type germanium it should be doped with a
(A) Trivalent impurity. (B) Tetravalent impurity.
(C) Pentavalent impurity. (D) Any of the above will do.
Ans: A
Q.45 Barrier potential in a P-N junction is caused by
(A) Thermally generated electrons and holes.
(B) Diffusion of majority carriers across the junction.
(C) Migration of minority carriers across the junction.
(D) Flow of drift current.
Ans: B
Q.46 The heating elements of electric irons are made of
(A) Copper. (B) Nichrome.
(C) Constantan. (D) Aluminium.
Ans: B
Q.47 The most malleable, ductile low resistivity material is
(A) Copper. (B) Aluminium.
(C) Silver. (D) Iron.
Ans: C
Q.48 The percentage of carbon in mild steel is
(A) 0.08 to 0.3 % (B) 0.5 to 1.4 %
(D) 2.35 % (D) 0.5 %
Ans: A
Q.49 Aluminium is
(A) Silvery white in colour. (B) Yellow in colour.
(C) Reddish in colour. (D) Pale yellow in colour.
Ans: A
Q.50 Hard ferrites are used for making
(A) Transformer cores. (B) Electrical machinery.
(C) High frequency equipment. (D) Light weight permanent magnets.
Ans: D
Q.51 The main constituents of glass is
(A) SiO2 (B) B2O3
(C) Al2O3 (D) Cr2O3
Ans: A
Q.52 Micanite is a form of
(A) Built up mica.
(B) Hydrated potassium aluminium silicate.
(C) Magnesium mica.
(D) Calcium mica.
Q.53
Ans: A
What is the type of bonding in silicon?
(A) Ionic.
(C) Metallic.
(B) Covalent.
(D) Ionic + Metallic
Ans: B
Q.54 P-N junction is
(A) a rectifier. (B) an amplifier.
(C) an Oscillator. (D) a Coupler.
Ans: A
Q.55 The conductivity of an extrinsic semiconductor
(A) decreases with temperature.
(B) increases with temperature.
(C) remains constant with temperature.
(D) decreases and then increases with temperature.
Ans: B
Q.56 When a semiconductor is doped with a P-type impurity, each impurity atom will
(A) acquire negative charge. (B) acquire positive charge.
(C) remain electrically neutral. (D) give away one electron.
Ans: A
Q.57 Number of Terminals in a MOSFET are
(A) Two (B) Three
(C) Four (D) Five
Ans: B
PKR ELECTRICAL ENGINEERING
Q.58 Which of the following material has the highest melting point
(A) Copper. (B) Aluminium.
(C) Tungsten. (D) Gold.
Ans: C
Q.59 Bronze is an alloy of
(A) Copper and Tin. (B) Copper and Steel.
(C) Copper and Mercury. (D) Copper and Aluminium.
Ans: A
Q.60 A transistor has
(A) One p-n junction. (B) Two p-n junction.
(C) Four p-n junction. (D) Five p-n junction.
Ans: B
Q.61 Example of high resistivity material is
(A) Nichrome (B) Silver
(C) Gold (D) Copper
Ans: A
Q.62 Hard magnetic materials are used for making
(A) Permanent magnets. (B) Temporary magnets.
(C) Conductors. (D) Insulator.
Ans: A
Q.63 Hall effect is associated with
(A) Conductors. (B) Semiconductors.
(C) Thermistors. (D) Solders.
Ans: B
Q.64 Addition of trivalent impurity to a semiconductor creates many
(A) holes. (B) free electrons.
(C) valance electrons. (D) bound electrons.
Ans: B
Q.65 Magnetic materials
(A) provide path to magnetic flux. (B) are good insulators.
(C) are semiconductors. (D) None.
Ans: A
Q.66 In a ferromagnetic material the state of flux density is as follows when external magnetic
field is applied to it.
(A) Increased (B) Decreased
(C) Remains unchanged (D) Becomes zero
Ans: C
Q.67 Paper is hygroscopic and absorbent.
(A) True (B) False
Ans: A
Q.68 Insulators have
(A) A full valence band. (B) An empty conduction band.
(C) A large energy gap. (D) All the above.
Ans: C
Q.69 Hysteresis loss least depends on
(A) Frequency. (B) Magnetic field intensity.
(C) Volume of the material. (D) Grain orientation of material.
Ans: D
Q.70 Atoms with four valence electrons are good conductors.
(A) True (B) False
Ans: B
Q.71 Semi-conductors have temperature coefficient of resistance.
(A) Negative (B) Positive
(C) Both positive and negative (D) None of the above
Ans: A
Q.72 Tick off the material, which is different from the group
(A) Constantan. (B) Manganin.
(C) Nichrome. (D) Brass.
Ans: D
Q.73 Tick of the property, which is different from the group
(A) Ductility. (B) Resistivity.
(C) Tensile strength. (D) Hardness.
Ans: B
Q.74 Ferroelectric materials are characterised by
(A) Very high degree of polarisation.
(B) A sharp dependence of polarisation on temperature.
(C) Non-linear dependence of the charge Q on the applied voltage.
(D) All the above.
Ans: D
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