Quiz  /  Electrical Engineering Materials MCQ Interview Questions and Answers PDF

  • 1. 
    The converse of hardness is known as

  • malleability
  • toughness
  • softness
  • none of the above

  • 2. 
    On which of the following factors does the resistivity of a material depend ?

  • Resistance of the conductor
  • Area of the conductor section
  • Length of the conductor
  • All of the above

  • 3. 
    is a negatively charged particle present in an atom.

  • Proton
  • Neutron
  • Electron
  • None of the above

  • 4. 
    The tiny block formed by the arrangement of a small group of atoms is called the

  • unit cell
  • space lattice
  • either (a) or (b)
  • none of the above

  • 5. 
    The co-ordination number of a simple cubic structure is

  • 2
  • 4
  • 6
  • 8

  • 6. 
    The covalent bond is formed by

  • transfer of electrons between atoms
  • sharing of electrons between atoms
  • sharing of variable number of electrons by a variable number of atoms
  • none of the above

  • 7. 
    A perfect conductor has

  • zero conductivity
  • unity conductivity
  • infinite conductivity
  • none of the above

  • 8. 
    The metal having the lowest temperature coefficient of resistance is

  • gold
  • copper
  • aluminium
  • kanthal

  • 9. 
    Commonly used conducting materials are

  • copper
  • aluminium
  • both (a) and (b)
  • copper and silver
  • platinum and gold

  • 10. 
    Which of the following materials is preferred for transmitting electrical energy over long distance ?

  • Copper
  • Aluminium
  • Steel reinforced copper
  • Steel reinforced aluminium

  • 11. 
    The kinetic energy of a bounded electron is (6) greater than that of unbounded electron

  • less than that of unbounded electron
  • equal to that of unbounded electron
  • infinite
  • none of the above

  • 12. 
    The conductivity of a conductor can be increased by

  • decreasing its temperature
  • increasing its temperature
  • decreasing its vibration
  • increasing its vibration

  • 13. 
    Superconductivity is observed for

  • infrared frequencies
  • d.c. and low frequency
  • a.c. and high frequency
  • frequencies having no effect
  • none of the above

  • 14. 
    The superconductivity is due to

  • the crystal structure having no atomic vibration at 0°K
  • all electrons interact in the super-conducting state
  • the electrons jump into nucleus at 0°K
  • none of the above

  • 15. 
    The value of critical field below the transition temperature will

  • increase
  • decrease
  • remain unchanged
  • any of the above

  • 16. 
    In a superconductor the value of critical density depends upon

  • magnetic field strength
  • temperature
  • either (a) or (b)
  • both (a) and (b)

  • 17. 
    Superconductors are becoming popular for use in

  • generating very strong magnetic field
  • manufacture of bubble memories
  • generating electrostatic field
  • generating regions free from magnetic field

  • 18. 
    Mercury as an electric contact material is

  • a liquid
  • a metal
  • a metal liquid
  • a gas

  • 19. 
    An H.R.C. fuse is

  • a ceramic body having metal and caps
  • a wire of platinum
  • a heavy cross-section of copper or aluminium
  • a ceramic tube having carbon rod inside it

  • 20. 
    Which of the following resistive materials has the lowest temperature co-efficient of resistance ?

  • Nichrome
  • Constantan
  • Kanthal
  • Molybdenum

  • 21. 
    The coils of D.C. motor starter are wound with wire of

  • copper
  • kanthal
  • manganin
  • nichrome

  • 22. 
    The conductors have transport phenomena of electrons due to

  • electric field
  • magnetic field
  • electromagnetic field
  • none of the above

  • 23. 
    By increasing impurity content in the metal alloy the residual resistivity always

  • decreases
  • increases
  • remains constant
  • becomes temperature independent

  • 24. 
    The structure sensitive property of a super conductor is

  • critical magnetic field
  • transition temperature
  • critical current density
  • none of the above

  • 25. 
    Which of the following variety of copper has the best conductivity ?

  • Induction hardened copper
  • Hard drawn copper
  • Pure annealed copper
  • Copper containing traces of silicon

  • 26. 
    Constantan contains

  • silver and tin
  • copper and tungsten
  • tungsten and silver
  • copper and nickel

  • 27. 
    Which of the following is the poorest conductor of electricity ?

  • Carbon
  • Steel
  • Silver
  • Aluminium

  • 28. 
    ______ has zero temperature co-efficient of resistance.

  • Aluminium
  • Carbon
  • Porcelain
  • Manganin

  • 29. 
    Piezoelectric materials serve as a source of _____ .

  • resonant waves
  • musical waves
  • microwaves
  • ultrasonic waves

  • 30. 
    In thermocouples which of the following pairs is commonly used ?

  • Copper-constantan
  • Aluminium-tin
  • Silver-German silver
  • Iron-steel

  • 31. 
    Carbon electrodes are not used in

  • GLS lamps
  • electric arc furnace
  • dry cells
  • cinema projectors

  • 32. 
    Solder is an alloy of

  • copper and aluminium
  • tin and lead
  • nickel, copper and zinc
  • silver, copper and lead

  • 33. 
    ______ is most commonly used for making magnetic recording tape

  • Silver nitrate
  • Ferric oxide
  • Small particles of iron
  • Silicon-iron

  • 34. 
    Overhead telephone wires are made of

  • aluminium
  • steel
  • ACSR conductors
  • copper

  • 35. 
    ______ is an example of piezoelectric material.

  • Glass
  • Quartz
  • Corrundum
  • Neoprene

  • 36. 
    _____ is the main constituent of glass

  • Fe203
  • Si02
  • AI2O3
  • B2O3

  • 37. 
    A good electric contact material should have all of the following properties except

  • high resistivity
  • high resistance to corrosion
  • good thermal conductivity
  • high melting point

  • 38. 
    Most of the common metals have _____ structure.

  • linear
  • hexagonal
  • orthorhombic
  • cubic

  • 39. 
    Which of the following affect greatly the resistivity of electrical conductors ?

  • Composition
  • Pressure
  • Size
  • Temperature

  • 40. 
    Thermonic emission occurs in

  • vacuum tubes
  • copper conductors
  • ferrite cores
  • transistors

  • 41. 
    Super conductivity can be destroyed by

  • adding impurities
  • reducing temperatures
  • application of magnetic field
  • any of the above

  • 42. 
    Non-linear resistors

  • produce harmonic distortion
  • follows Ohm’s law at low temperatures only
  • result in non-uniform heating
  • none of the above

  • 43. 
    A carbon resistor contains

  • carbon crystals
  • solid carbon granules
  • pulverized coal
  • finely divided carbon black.

  • 44. 
    In graphite, bonding is

  • covalent
  • metallic
  • Vander Waals
  • Vander Waals and covalent

  • 45. 
    Total number of crystal systems is

  • 2
  • 4
  • 7
  • 12

  • 46. 
    The number of atoms per unit cell in B.C.C. structure is

  • 1
  • 2
  • 4
  • 8

  • 47. 
    Which of the following material is not a semiconductor ?

  • Silica
  • Germanium
  • Selenium
  • Gallium-arsenide

  • 48. 
    Carbon resistors are used extensively because they are

  • easy to make
  • compact
  • inexpensive
  • all of the above reasons

  • 49. 
    Carbon rods are used in wet and dry cells because

  • carbon rod serves as conductor
  • carbon can resist the attack of battery acid
  • both (a) and (b)
  • either (a) or (b)

  • 50. 
    Due to which of the following factors the brush wear rate is altered ?

  • Speed of the machine
  • Contact pressure
  • Surface conditions of brush and commutator
  • Excessive sparking
  • All of the above

  • 51. 
    Which of the following are non-conductors of electricity?

  • Non-metal solids except carbon
  • Air and most other gases
  • Pure water and liquids in general except mercury
  • All of the above

  • 52. 
    Carbon bearings are used under which of the following conditions ?

  • Where lubrication is difficult or im-possible
  • Where corrosive chemical action exists
  • Where high temperature exists
  • All of the above

  • 53. 
    Which of the following high resistance materials has the highest operating temperature ?

  • Kanthal
  • Manganin
  • Nichrome
  • Eureka

  • 54. 
    Steel wire is used as

  • overhead telephone wire
  • earth wire
  • core wire of ACSR
  • all of the above

  • 55. 
    Low resistivity materials are used in

  • transformer, motor and generator windings
  • transmission and distribution lines
  • house wiring
  • all above applications

  • 56. 
    Platinum is used in

  • electrical contacts
  • thermocouple
  • heating element in high temperature furnace
  • grids of special purpose vacuum tubes
  • all of the above

  • 57. 
    Which of the following is an advantage of stranded conductor over equivalent single conductor ?

  • Less liability to kink
  • Greater flexibility
  • Less liability to break
  • All of the above

  • 58. 
    Due to which of the following reasons copper and aluminium are not used for heating elements ?

  • Both have great tendency for oxidation
  • Both have low melting point
  • Very large length of wires will be required
  • All of the above

  • 59. 
    Copper, even though costly, finds use in the windings of electrical machines because

  • copper points offer low contact resistance
  • copper can be easily soldered and welded
  • copper windings are less bulky and the machines become compact
  • all of the above

  • 60. 
    Which of the following materials is used for making coils of standard resistances ?

  • Copper
  • Nichrome
  • Platinum
  • Manganin

  • 61. 
    Substances whose specific resistance abruptly decreases at very low temperature are called

  • insulators
  • conductors
  • semiconductors
  • superconductors

  • 62. 
    Which of the following materials is the best conductor of electricity ?

  • Tungsten
  • Aluminium
  • Copper
  • Carbon

  • 63. 
    is the property of absorbing moisture from atmosphere.

  • Solubility
  • Viscosity
  • Porosity
  • Hygroscopicity

  • 64. 
    Thermocouples are mainly used for the measurement of

  • temperature
  • resistance
  • eddy currents
  • coupling co-efficient

  • 65. 
    The conduction of electricity, in semiconductors, takes place due to movement of

  • positive ions only
  • negative ions only
  • positive and negative ions
  • electrons and holes

  • 66. 
    Which of the following is a semiconductor material ?

  • Phosphorous
  • Rubber
  • Silicon
  • Aluminium

  • 67. 
    Selenium is _____ semiconductor.

  • extrnisic
  • intmisic
  • N-type
  • P-type

  • 68. 
    ________ has the best damping properties.

  • Diamond
  • High speed steel
  • Mild steel
  • Cast iron

  • 69. 
    The photo-electric effect occurs only when the incident light has more than a certain critical

  • intensity
  • speed
  • frequency
  • wave length

  • 70. 
    If the resistance of a conductor does not vary in accordance with Ohm’s law it is known as

  • non-linear conductor
  • reverse conductor
  • bad-conductor
  • non-conductor

  • 71. 
    Spark plug makes use of which of the following materials for insulation ?

  • Porcelain
  • Slate
  • Asbestos
  • Glass

  • 72. 
    The forbidden gap in an insulator is

  • large
  • small
  • nil
  • any of the above

  • 73. 
    Which of the following factors affect resistivity of metals ?

  • Age hardening
  • Alloying
  • Temperature
  • Cold work
  • All of the above

  • 74. 
    Effect of moisture on the insulating materials is to

  • decrease dielectric constant
  • decrease dielectric strength
  • decrease insulation resistance
  • increase dielectric loss
  • all of the above

  • 75. 
    Surface resistance of an insulating material is reduced due to the

  • smoky and dirty atmosphere
  • humidity in the atmosphere
  • both (a) and (b)
  • neither (a) nor (b)

  • 76. 
    Superconducting metal in super conducting state has relative permeability of

  • zero
  • one
  • negative
  • more than one

  • 77. 
    In conductors conduction of electricity takes place due to movement of

  • electrons only
  • positive ions only
  • negative ions only
  • positive and negative ions
  • none of the above

  • 78. 
    The carbon percentage is least in

  • low carbon steel
  • wrought iron
  • cast iron
  • malleable iron

  • 79. 
    The current due to electron flow in conduction band is the hole current in valence band.

  • equal to
  • less than
  • greater than
  • any of the above

  • 80. 
    For a hole which of the following statements is incorrect ?

  • Holes can exist in certain semiconductors only
  • Holes can exist in any material including conductors
  • Holes may constitute an electric current
  • Holes can be considered as a net positive charge

  • 81. 
    is an element used in semiconductors whose atoms have three valence electrons.

  • An acceptor
  • A donor
  • Germanium
  • Silicon

  • 82. 
    The minority carrier concentration is largely a function of

  • forward biasing voltage
  • reverse biasing voltage
  • temperature
  • the amount of doping
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