electrical engineering materials MCQs – Page 2

Practise focused electrical engineering materials questions with marked answers for exam preparation and subject revision.

electrical engineering materials Mcqs
51. Most of the common metals have _________ structure?
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A. orthorhombic

B. hexagonal

C. cubic

D. linear

52. The covalent bond is formed by_______________?
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A. none of the above

B. transfer of electrons between atoms

C. sharing of variable number of electrons by a variable number of atoms

D. sharing of electrons between atoms
53. Which of the following is the poorest conductor of electricity ?
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A. Aluminium

B. Carbon

C. Steel

D. Silver

54. For a particular material the Hall coefficient was found to be zero. The material is______________?
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A. insulator

B. none of the above

C. intrinsic semiconductor

D. metal
55. A good electric contact material should have all of the following properties except_____________?
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A. high melting point

B. high resistance to corrosion

C. high resistivity

D. good thermal conductivity

56. The conductors have transport phenomena of electrons due to____________?
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A. electric field

B. none of the above

C. magnetic field

D. electromagnetic field

57. The impurity atoms is semiconductors_____________?
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A. inject more charge carriers

B. increase the kinetic energy of valence electrons

C. reduce the energy gap

D. all of the above

58. In a crystal, an atom vibrates at a frequency determined by_______________?
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A. the heat content of the crystal

B. the temperature of the crystal

C. the stiffness of the bonds it makes with neighbors
59. If the resistance of a conductor does not vary in accordance with Ohms law it is known as____________?
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A. bad-conductor

B. reverse conductor

C. non-conductor

D. non-linear conductor
60. A perfect conductor has_____________?
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A. unity conductivity

B. none of the above

C. infinite conductivity

D. zero conductivity

61. Thermonic emission occurs in______________?
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A. vacuum tubes

B. transistors

C. ferrite cores

D. copper conductors

62. By increasing impurity content in the metal alloy the residual resistivity always_____________?
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A. decreases

B. remains constant

C. increases

D. becomes temperature independent

63. The converse of hardness is known as______________?
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A. softness

B. toughness

C. none of the above

D. malleability

64. The kinetic energy of a bounded electron is______________?
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A. infinite

B. none of the above

C. greater than that of unbounded electron

D. less than that of unbounded electron

E. equal to that of unbounded electron

65. Non-linear resistors______________?
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A. produce harmonic distortion

B. none of the above

C. follows Ohms law at low temperatures only

D. result in non-uniform heating

66. The photo-electric effect occurs only when the incident light has more than a certain critical____________?
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A. speed

B. wave length

C. frequency

D. intensity

67. The resistivity of a metal is a function of temperature because_____________?
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A. the electron density varies with temperature

B. the amplitude of vibration of the atoms varies with temperature

C. the electron gas density varies with temperature

68. In conductors conduction of electricity takes place due to movement of_______________?
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A. negative ions only

B. electrons only

C. none of the above

D. positive and negative ions

E. positive ions only

69. Piezoelectric materials serve as a source of ____________ ?
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A. resonant waves

B. ultrasonic waves

C. musical waves

D. microwaves

70. Which of the following high resistance materials has the highest operating temperature ?
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A. Kanthal

B. Eureka

C. Nichrome

D. Manganin

71. The transition temperature of mercury is____________?
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A. 4.12K

B. 9.22K

C. 1.14K

D. 18.0K

72. Overhead telephone wires are made of_____________?
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A. steel

B. ACSR conductors

C. aluminium

D. copper

73. Which of the following variety of copper has the best conductivity ?
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A. Pure annealed copper

B. Hard drawn copper

C. Induction hardened copper

D. Copper containing traces of silicon

74. Constantan contains_______________?
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A. copper and nickel

B. tungsten and silver

C. copper and tungsten

D. silver and tin

75. The tiny block formed by the arrangement of a small group of atoms is called the____________?
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A. either A. or (b)

B. none of the above

C. space lattice

D. unit cell
76. The conductivity of an extrinsic semiconductor with temperature________________?
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A. increases

B. decreases

C. remains constant
77. The structure sensitive property of a super conductor is______________?
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A. transition temperature

B. critical current density

C. none of the above

D. critical magnetic field

78. The coils of D.C. motor starter are wound with wire of_______________?
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A. kanthal

B. copper

C. nichrome

D. manganin
79. Which of the following factors affect resistivity of metals ?
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A. Age hardening

B. Alloying

C. All of the above

D. Temperature

E. Cold work

80. In a superconductor the value of critical density depends upon______________?
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A. magnetic field strength

B. temperature

C. either (A) or (B)

D. both (A) and (B)
81. An H.R.C. fuse is_______________?
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A. a wire of platinum

B. a ceramic tube having carbon rod inside it

C. a ceramic body having metal and caps

D. a heavy cross-section of copper or aluminium

82. Due to which of the following reasons copper and aluminium are not used for heating elements ?
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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 above
83. The carbon percentage is least in__________________?
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A. wrought iron

B. malleable iron

C. cast iron

D. low carbon steel

84. Superconducting metal in super conducting state has relative permeability of________________?
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A. one

B. more than one

C. negative

D. zero
85. Which of the following materials does not have covalent bonds ?
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A. Silicon

B. Organic polymers

C. Metals
86. Which of the following affect greatly the resistivity of electrical conductors ?
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A. Size

B. Pressure

C. Composition

D. Temperature

87. ___________ is most commonly used for making magnetic recording tape?
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A. Ferric oxide

B. Silver nitrate

C. Silicon-iron

D. Small particles of iron

88. Low resistivity materials are used in__________?
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A. transformer, motor and generator windings

B. transmission and distribution lines

C. house wiring

D. all above applications
89. Superconductivity is observed for____________?
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A. none of the above

B. a.c. and high frequency

C. frequencies having no effect

D. infrared frequencies

E. d.c. and low frequency
90. Which of the following resistive materials has the lowest temperature co-efficient of resistance ?
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A. Constantan

B. Molybdenum

C. Kanthal

D. Nichrome
91. Effect of moisture on the insulating materials is to________________?
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A. all of the above

B. decrease dielectric constant

C. increase dielectric loss

D. decrease insulation resistance

E. decrease dielectric strength

92. Super conductivity can be destroyed by_____________?
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A. any of the above

B. reducing temperatures

C. application of magnetic field

D. adding impurities

93. Substances whose specific resistance abruptly decreases at very low temperature are called___________?
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A. conductors

B. semiconductors

C. insulators

D. superconductors
94. is a negatively charged particle present in an atom______________?
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A. Electron

B. Proton

C. Neutron

D. None of the above

95. The formula __________ determines the number of electrons that can be accommodated in any level?
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A. 4ns

B. 2n3

C. 4n2

D. 2n2
96. For germanium the forbidden energy gap is_______________?
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A. 0.15 eV

B. 0.7eV

C. 0.25 eV

D. 0.5eV

97. The metal having the lowest temperature coefficient of resistance is_________________?
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A. aluminium

B. gold

C. copper

D. kanthal

98. Carbon rods are used in wet and dry cells because_____________?
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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)

99. Carbon electrodes are not used in_______________?
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A. electric arc furnace

B. GLS lamps

C. dry cells

D. cinema projectors

100. Which of the following materials is the best conductor of electricity ?
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A. Carbon

B. Copper

C. Tungsten

D. Aluminium