100 TOP Electrical Engineering Materials - Electrical
Engineering Multiple choice Questions and Answers | MCQs
preparation for Engineering Competitive Exams
Latest Electrical Engineering Materials Questions and
Answers
1. The converse of hardness is known as(a) malleability (b)
toughness(c) softness(d) none of the aboveAns: c
2. On which of the following factors does the resistivity of a
material depend ?(a) Resistance of the conductor(b) Area of the
conductor section(c) Length of the conductor(d) All of the
aboveAns: d
3. is a negatively charged particle present in an atom.(a)
Proton (b) Neutron(c) Electron(d) None of the aboveAns: c
4. The formula ____ determines the number of electrons that can
be accommodated in any level.(a) 2n2 (6) 4n2(c) 2n3 (d) 4nsAns:
a
5. The tiny block formed by the arrangement of a small group of
atoms is called the(a) unit cell (b) space lattice(c) either (a) or
(b)(d) none of the aboveAns: a
6. The co-ordination number of a simple cubic structure is(a) 2
(b) 4(c) 6 (d) 8Ans: c
7. The covalent bond is formed by(a) transfer of electrons
between atoms(b) sharing of electrons between atoms(e) sharing of
variable number of electrons by a variable number of atoms(d) none
of the aboveAns: b
8. A perfect conductor has(a) zero conductivity(b) unity
conductivity(c) infinite conductivity(d) none of the aboveAns:
c
9. The metal having the lowest temperature coefficient of
resistance is(a) gold (b) copper(c) aluminium (d) kanthalAns: a
10. Commonly used conducting materials are(a) copper (b)
aluminium(c) both (a) and (b)(d) copper and silver(e) platinum and
goldAns: c
11. Which of the following materials is preferred for
transmitting electrical energy over long distance ?(a) Copper (b)
Aluminium(c) Steel reinforced copper(d) Steel reinforced
aluminiumAns: d
12. The kinetic energy of a bounded electron is(a) less than
that of unbounded electron(6) greater than that of unbounded
electron(c) equal to that of unbounded electron(d) infinite(e) none
of the aboveAns: a
13. A highly conductive material must have(a) highest
conductivity(b) lowest temperature co-efficient(c) good mechanical
strength(d) good corrosion resistance(e) easy solderable and
drawable quality(f) all of the aboveAns: f
14. The conductivity of a conductor can be increased by(a)
decreasing its temperature(b) increasing its temperature(c)
decreasing its vibration(d) increasing its vibrationAns: a
15. Superconductivity is observed for(a) infrared frequencies(b)
d.c. and low frequency(c) a.c. and high frequency(d) frequencies
having no effect(e) none of the aboveAns: b
16. The superconductivity is due to(a) the crystal structure
having no atomic vibration at 0K(b) all electrons interact in the
super-conducting state(c) the electrons jump into nucleus at 0K(d)
none of the aboveAns: a
17. The value of critical field below the transition temperature
will(a) increase (b) decrease(c) remain unchanged(d) any of the
aboveAns: a
18. In a superconductor the value of critical density depends
upon(a) magnetic field strength (b) temperature(c) either (a) or
(b)(d) both (a) and (b)Ans: d
19. Superconductors are becoming popular for use in(a)
generating very strong magnetic field(b) manufacture of bubble
memories(c) generating electrostatic field(d) generating regions
free from magnetic fieldAns: a
20. High resistivity materials are used in(a) precision
instruments(6) heating elements(c) motor starters(d) incandescent
lamps(e) all of the aboveAns: e
21. Mercury as an electric contact material is(a) a liquid (b) a
metal(c) a metal liquid (d) a gasAns: c
22. An H.R.C. fuse is(a) a ceramic body having metal and caps(b)
a wire of platinum(c) a heavy cross-section of copper or
aluminium(d) a ceramic tube having carbon rod inside itAns: a
23. Which of the following resistive materials has the lowest
temperature co-efficient of resistance ?(a) Nichrome (b)
Constantan(c) Kanthal (d) MolybdenumAns: a
24. The coils of D.C. motor starter are wound with wire of(a)
copper (b) kanthal(c) manganin (d) nichromeAns: c
25. The conductors have transport phenomena of electrons due
to(a) electric field (b) magnetic field(c) electromagnetic field(d)
none of the aboveAns: a
26. The transition temperature of mercury is(a) 18.0K (6)
9.22K(c) 4.12K (d) 1.14'KAns: c
27. By increasing impurity content in the metal alloy the
residual resistivity always(a) decreases (b) increases(c) remains
constant(d) becomes temperature independentAns: b
28. The structure sensitive property of a super conductor is(a)
critical magnetic field(b) transition temperature(c) critical
current density(d) none of the aboveAns: c
29. At transition temperature the value of critical field is(a)
zero(6) negative real value(c) positive real value(d) complex
valueAns: a
30. Which of the following variety of copper has the best
conductivity ?(a) Induction hardened copper(b) Hard drawn copper(c)
Pure annealed copper (d) Copper containing traces of siliconAns:
c
31. Constantan contains(a) silver and tin(b) copper and tungsten
(c) tungsten and silver(d) copper and nickelAns: d
32. Which of the following is the poorest conductor of
electricity ?(a) Carbon (b) Steel(c) Silver (d) AluminiumAns: a
33 ______ has zero temperature co-efficient of resistance.(a)
Aluminium (b) Carbon(c) Porcelain (d) ManganinAns: d
34. Piezoelectric materials serve as a source of _____ . (a)
resonant waves(b) musical waves(c) microwaves (d) ultrasonic
wavesAns: d
35. In thermocouples which of the following pairs is commonly
used ?(a) Copper-constantan(b) Aluminium-tin (c) Silver-German
silver(d) Iron-steelAns: a
36 is viscoelastic.(a) Cast-iron (6) Graphite (c) Rubber (d)
GlassAns: c
37. Carbon electrodes are not used in(a) GLS lamps(b) electric
arc furnace (c) dry cells(d) cinema projectorsAns: a
38. Solder is an alloy of(a) copper and aluminium (b) tin and
lead(c) nickel, copper and zinc(d) silver, copper and leadAns:
b
39 ______ is most commonly used for making magnetic recording
tape (a) Silver nitrate(b) Ferric oxide(c) Small particles of
iron(d) Silicon-ironAns: b
40. Overhead telephone wires are made of(a) aluminium (b) steel
(c) ACSR conductors(d) copperAns: b
41. ______ is an example of piezoelectric material.(a) Glass (b)
Quartz(c) Corrundum (d) NeopreneAns: b
42. _____ is the main constituent of glass(a) Fe203 (b) Si02(c)
AI2O3 (d) B2O3Ans: b
43. A good electric contact material should have all of the
following properties except(a) high resistivity(b) high resistance
to corrosion(c) good thermal conductivity(d) high melting pointAns:
a
44. Most of the common metals have _____ structure.(a) linear
(b) hexagonal(c) orthorhombic (d) cubicAns: d
45. Which of the following affect greatly the resistivity of
electrical conductors ?(a) Composition (b) Pressure(c) Size (d)
TemperatureAns: a
46. Thermonic emission occurs in(a) vacuum tubes(b) copper
conductors(c) ferrite cores (d) transistorsAns: a
47. _____ is a hard solder.(a) Tin-lead (6) Tin-silver-lead(c)
Copper-zinc(d) None of the aboveAns: c
48. Addition of 0.3 to 4.5% silicon to iron _____ the electrical
resistivity of iron.(a) increases (b) decreases(c) does not
changeAns: a
49. Super conductivity can be destroyed by(a) adding
impurities(b) reducing temperatures(c) application of magnetic
field(d) any of the aboveAns: c
50. Non-linear resistors(a) produce harmonic distortion(b)
follows Ohm's law at low temperatures only(c) result in non-uniform
heating(d) none of the aboveAns: a
51. A carbon resistor contains(a) carbon crystals(b) solid
carbon granules(c) pulverized coal(d) finely divided carbon
black.Ans: d
52. Which of the following materials does not have covalent
bonds ?(a) Organic polymers(b) Silicon (c) MetalsAns: c
53. In graphite, bonding is(a) covalent (b) metallic(c) Vander
Waals(d) Vander Waals and covalentAns: d
54. Total number of crystal systems is(a) 2 (b) 4(c) 7 (d)
12Ans: c
55. The number of atoms per unit cell in B.C.C. structure is(a)
1 (b) 2(c) 4 (d) 8Ans: b
56. The conductivity of a metal is determined by(a) the
electronic concentration and the mobility of the free electrons(6)
the number of valence electrons per atom(c) either (a) or (b)(d)
none of the aboveAns: a
57. The resistivity of a metal is a function of temperature
because(a) the amplitude of vibration of the atoms varies with
temperature(b) the electron density varies with temperature(c) the
electron gas density varies with temperatureAns: a
58. In a crystal, an atom vibrates at a frequency determined
by(a) the heat content of the crystal(b) the temperature of the
crystal(c) the stiffness of the bonds it makes with neighborsAns:
c
59. Due to which of the following reasons aluminium does not
corrode in atmosphere ?(a) Aluminium is a noble metal(b)
Atmospheric oxygen can only diffuse very slowly through the oxide
layer which is formed on the surface of aluminium(c) No reaction
with oxygen occurs ft Any of the aboveAns: b
60. The impurity atoms is semiconductors(a) inject more charge
carriers(6) reduce the energy gap(c) increase the kinetic energy of
valence electrons(d) all of the aboveAns: b
61. Which of the following material is not a semiconductor ?(a)
Silica (b) Germanium(c) Selenium (d) Gallium-arsenideAns: a
62. Carbon resistors are used extensively because they are(a)
easy to make (b) compact(c) inexpensive(d) all of the above
reasonsAns: d
63. Carbon rods are used in wet and dry cells because(a) carbon
rod serves as conductor(b) carbon can resist the attack of battery
acid(c) both (a) and (b)(d) either (a) or (b)Ans: c
64. Due to which of the following factors the brush wear rate is
altered ?(a) Speed of the machine(b) Contact pressure(c) Surface
conditions of brush and commutator(d) Excessive sparking(e) All of
the aboveAns: e
65. Which of the following are non-conductors of electricity?(a)
Non-metal solids except carbon(b) Air and most other gases(c) Pure
water and liquids in general except mercury(d) All of the aboveAns:
d
66. Carbon bearings are used under which of the following
conditions ?(a) Where lubrication is difficult or im-possible(b)
Where corrosive chemical action exists(c) Where high temperature
exists(d) All of the aboveAns: d
67. Which of the following high resistance materials has the
highest operating temperature ?(a) Kanthal (b) Manganin(c) Nichrome
(d) EurekaAns: a
68. Steel wire is used as(a) overhead telephone wire(b) earth
wire(c) core wire of ACSR(d) all of the above Ans: d
69. Low resistivity materials are used in(a) transformer, motor
and generator windings(b) transmission and distribution lines(c)
house wiring(d) all above applicationsAns: d
70. Platinum is used in(a) electrical contacts(b)
thermocouple(c) heating element in high temperature furnace(d)
grids of special purpose vacuum tubes(e) all of the aboveAns: e
71. Which of the following is an advantage of stranded conductor
over equivalent single conductor ?(a) Less liability to kink(b)
Greater flexibility(c) Less liability to break(d) All of the
aboveAns: d
72. Due to which of the following reasons copper and aluminium
are not used for heating elements ?(a) Both have great tendency for
oxidation(b) Both have low melting point(c) Very large length of
wires will be required(d) All of the aboveAns: d
73. Copper, even though costly, finds use in the windings of
electrical machines because(a) copper points offer low contact
resistance(b) copper can be easily soldered and welded(e) copper
windings are less bulky and the machines become compact(d) all of
the aboveAns: d
74. Which of the following materials is used for making coils of
standard resistances ?(a) Copper (b) Nichrome(c) Platinum (d)
ManganinAns: d
75. Substances whose specific resistance abruptly decreases at
very low temperature are called(a) insulators (b) conductors(c)
semiconductors(d) superconductorsAns: d
76. Which of the following materials is the best conductor of
electricity ?(a) Tungsten (b) Aluminium(c) Copper (d) CarbonAns:
c
77. is the property of absorbing moisture from atmosphere.(a)
Solubility (b) Viscosity(c) Porosity (d) HygroscopicityAns: d
78. Thermocouples are mainly used for the measurement of(a)
temperature (b) resistance(c) eddy currents(d) coupling
co-efficientAns: a
79. Due to which of the following fact, in India, aluminium is
replacing copper ?(a) Aluminium is more ductile and malleable than
copper(6) Aluminium is available in plenty, cheaper and lighter
than copper(c) Aluminium has lower resistivity than that of
copper(d) Aluminium has less temperature co-efficient than
copperAns: b
80. The conduction of electricity, in semiconductors, takes
place due to movement of(a) positive ions only(b) negative ions
only(c) positive and negative ions(d) electrons and holesAns: d
81. Which of the following is a semiconductor material ?(a)
Phosphorous (b) Rubber(c) Silicon (d) AluminiumAns: c
82. Selenium is _____ semiconductor.(a) extrnisic (b)
intmisic(c) N-type (d) P-typeAns: b
83. ________ has the best damping properties.(a) Diamond (b)
High speed steel(c) Mild steel (d) Cast ironAns: d
84. The photo-electric effect occurs only when the incident
light has more than a certain critical(a) intensity (b) speed(c)
frequency (d) wave lengthAns: c
85. If the resistance of a conductor does not vary in accordance
with Ohm's law it is known as(a) non-linear conductor(b) reverse
conductor(c) bad-conductor (d) non-conductorAns: a
86. Spark plug makes use of which of the following materials for
insulation ?(a) Porcelain (b) Slate(c) Asbestos (d) GlassAns: a
87. The forbidden gap in an insulator is(a) large (b) small(c)
nil(d) any of the aboveAns: a
88. Which of the following factors affect resistivity of metals
?(a) Age hardening(b) Alloying(c) Temperature (d) Cold work(e) All
of the aboveAns: e
89. Effect of moisture on the insulating materials is to(a)
decrease dielectric constant(b) decrease dielectric strength(c)
decrease insulation resistance(d) increase dielectric loss(e) all
of the aboveAns: e
90. Surface resistance of an insulating material is reduced due
to the(a) smoky and dirty atmosphere(b) humidity in the
atmosphere(c) both (a) and (b)(d) neither (a) nor (b)Ans: c
91. Superconducting metal in super conducting state has relative
permeability of(a) zero (b) one(c) negative (d) more than oneAns:
a
92. In conductors conduction of electricity takes place due to
movement of(a) electrons only(b) positive ions only(c) negative
ions only(d) positive and negative ions(e) none of the aboveAns:
a
93. The carbon percentage is least in(a) low carbon steel(b)
wrought iron(c) cast iron (d) malleable ironAns: b
94. For a particular material the Hall coefficient was found to
be zero. The material is(a) insulator (6) metal(c) intrinsic
semiconductor(d) none of the aboveAns: b
95. The conductivity of an extrinsic semiconductor with
temperature(a) decreases (b) increases(c) remains constantAns:
c
96. The current due to electron flow in conduction band isthe
hole current in valence band.(a) equal to (b) less than(c) greater
than(d) any of the aboveAns: c
97. For a hole which of the following statements is incorrect
?(a) Holes can exist in certain semiconductors only(b) Holes can
exist in any material including conductors(c) Holes may constitute
an electric current(d) Holes can be considered as a net positive
chargeAns: b
98. is an element used in semiconductors whose atoms have three
valence electrons.(a) An acceptor (b) A donor(c) Germanium (d)
SiliconAns: a
99. The minority carrier concentration is largely a function
of(a) forward biasing voltage(b) reverse biasing voltage(c)
temperature(d) the amount of dopingAns: c
100. For germanium the forbidden energy gap is(a) 0.15 eV (b)
0.25 eV(C) 0.5eV (d) 0.7eVAns: d
