PCBWay

Q 1. The kinetic energy of a bounded electron is

DRex Electronics

(A) Less than that of unbounded electron
(B) Greater than that of unbounded electron
(C) Equal to that of unbounded electron
(D) Infinite

Answer: Option A

 Q 2. 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 field

Answer: Option A

Q 3. Solder is an alloy of

(A) Copper and aluminium
(B) Tin and lead
(C) Nickel, Copper and zinc
(D) Silver, copper and lead

Answer: Option B

Q 4. Which of the following affect greatly the resistivity of electrical conductors?

(A) Composition
(B) Pressure
(C) Size
(D) Temperature

Answer: Option A

Q 5. 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 temperature
(D) None of the above

Answer: Option A

Q 6. 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) All of the above

Answer: Option D

Q 7. Substances whose specific resistance abruptly decreases at very low temperature are called

(A) Insulators
(B) Conductors
(C) Semiconductors
(D) Superconductors

Answer: Option D

Q 8. ________ has the best damping properties.

(A) Diamond
(B) High speed steel
(C) Mild steel
(D) Cast iron

Answer: Option D

Q 9. For a particular material the Hall coefficient was found to be zero. The material is

(A) Insulator
(B) Metal
(C) Intrinsic semiconductor
(D) None of the above

Answer: Option B

Q 10. 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 holes

Answer: Option D

Q 11. The photoelectric effect occurs only when the incident light has more than a certain critical

(A) Intensity
(B) Speed
(C) Frequency
(D) Wave length

Answer: Option C

Q 12. 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 above

Answer: Option D

Q 13. Which of the following material is not a semiconductor?

(A) Silica
(B) Germanium
(C) Selenium
(D) Gallium arsenide

Answer: Option A

Q 14. A carbon resistor contains

(A) Carbon crystals
(B) Solid carbon granules
(C) Pulverized coal
(D) Finely divided carbon black

Answer: Option D

Q 15. Overhead telephone wires are made of

(A) Aluminium
(B) Steel
(C) ACSR conductors
(D) Copper

Answer: Option B

Q 16. ________ has zero temperature coefficient of resistance.

(A) Aluminium
(B) Carbon
(C) Porcelain
(D) Manganin

Answer: Option D

Q 17. The transition temperature of mercury is

(A) 18.0°K
(B) 9.22°K
(C) 4.12°K
(D) 1.14°K

Answer: Option C

Q 18. The value of critical field below the transition temperature will

(A) Increase
(B) Decrease
(C) Remain unchanged
(D) Any of the above

Answer: Option A

Q 19. The coordination number of a simple cubic structure is

(A) 2
(B) 4
(C) 6
(D) 8

Answer: Option C

Q 20. Commonly used conducting materials are

(A) Copper
(B) Aluminium
(C) Both (A) and (B)
(D) Copper and silver

Answer: Option C

Q 21. Superconductivity is observed for

(A) Infrared frequencies
(B) D.C. and low frequency
(C) A.C. and high frequency
(D) Frequencies having no effect

Answer: Option B

Q 22. The structure sensitive property of a super conductor is

(A) Critical magnetic field
(B) Transition temperature
(C) Critical current density
(D) None of the above

Answer: Option C

Q 23.  _______ is viscoelastic.

(A) Cast iron
(B) Graphite
(C) Rubber
(D) Glass

Answer: Option C

Q 24. Addition of 0.3 to 4.5% silicon to iron ________ the electrical resistivity of iron.

(A) Increases
(B) Decreases
(C) Does not change
(D) None of the above

Answer: Option A

Q 25. 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 aluminium

Answer: Option D

Q 26. 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 neighbours
(D) None of the above

Answer: Option C

Q 27. Steel wire is used as

(A) Overhead telephone wire
(B) Earth wire
(C) Core wire of ACSR
(D) All of the above

Answer: Option D

Q 28. Due to which of the following fact, in India, aluminium is replacing copper?

(A) Aluminium is more ductile and malleable than copper
(B) Aluminium is available in plenty, cheaper and lighter than copper
(C) Aluminium has lower resistivity than that of copper
(D) Aluminium has less temperature coefficient than copper

Answer: Option B

Q 29. The carbon percentage is least in

(A) Low carbon steel
(B) Wrought iron
(C) Cast iron
(D) Malleable iron

Answer: Option B

Q 30. is a negatively charged particle present in an atom.

(A) Proton
(B) Neutron
(C) Electron
(D) None of the above

Answer: Option C

Q 31. Which of the following resistive materials has the lowest temperature coefficient of resistance?

(A) Nichrome
(B) Constantan
(C) Kanthal
(D) Molybdenum

Answer: Option A

Q 32. Piezoelectric materials serve as a source of ________.

(A) Resonant waves
(B) Musical waves
(C) Microwaves
(D) Ultrasonic waves

Answer: Option D

Q 33. Thermionic emission occurs in

(A) Vacuum tubes
(B) Copper conductors
(C) Ferrite cores
(D) Transistors

Answer: Option A

Q 34. The conductivity of a metal is determined by

(A) The electronic concentration and the mobility of the free electrons
(B) The number of valence electrons per atom
(C) Either (A) or (B)
(D) None of the above

Answer: Option A

Q 35. Which of the following high resistance materials has the highest operating temperature?

(A) Kanthal
(B) Manganin
(C) Nichrome
(D) Eureka

Answer: Option A

Q 36. Which of the following materials is the best conductor of electricity?

(A) Tungsten
(B) Aluminium
(C) Copper
(D) Carbon

Answer: Option C

Q 37. The forbidden gap in an insulator is

(A) Large
(B) Small
(C) Nil
(D) Any of the above

Answer: Option A

Q 38. The current due to electron flow in conduction band is the hole current in valence band.

(A) Equal to
(B) Less than
(C) Greater than
(D) Any of the above

Answer: Option C

Q 39. The converse of hardness is known as

(A) Malleability
(B) Toughness
(C) Softness
(D) None of the above

Answer: Option C

Q 40. The superconductivity is due to

(A) The crystal structure having no atomic vibration at 0°K
(B) All electrons interact in the superconducting state
(C) The electrons jump into nucleus at 0°K
(D) None of the above

Answer: Option A

Q 41. The metal having the lowest temperature coefficient of resistance is

(A) Gold
(B) Copper
(C) Aluminium
(D) Kanthal

Answer: Option A

Q 42. By increasing impurity content in the metal alloy the residual resistivity always

(A) Decreases
(B) Increases
(C) Remains constant
(D) Becomes temperature independent

Answer: Option B

Q 43. _______ is the main constituent of glass

(A) Fe2O3
(B) SiO2
(C) AI2O3
(D) B2O3

Answer: Option B

Q 44. Which of the following materials does not have covalent bonds?

(A) Organic polymers
(B) Silicon
(C) Metals
(D) None of the above

Answer: Option C

Q 45. 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 above

Answer: Option D

Q 46. Is the property of absorbing moisture from atmosphere?

(A) Solubility
(B) Viscosity
(C) Porosity
(D) Hygroscopicity

Answer: Option D

Q 47. Spark plug makes use of which of the following materials for insulation?

(A) Porcelain
(B) Slate
(C) Asbestos
(D) Glass

Answer: Option A

Q 48. 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

Answer: Option A

Q 49. Total number of crystal systems is

(A) 2
(B) 4
(C) 7
(D) 12

Answer: Option C

Q 50. 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 above

Answer: Option D

Q 51. 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 point

Answer: Option A

Q 52. In thermocouples which of the following pairs is commonly used?

(A) Copper-constantan
(B) Aluminium-tin
(C) Silver-German silver
(D) Iron-steel

Answer: Option A

Q 53. The coils of D.C. motor starter are wound with wire of

(A) Copper
(B) Kanthal
(C) Manganin
(D) Nichrome

Answer: Option C

Q 54. A highly conductive material must have

(A) Highest conductivity
(B) Lowest temperature coefficient
(C) Good mechanical strength & corrosion resistance
(D) All of the above

Answer: Option D

Q 55. 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 above

Answer: Option D

Q 56. Most of the common metals have _________ structure.

(A) Linear
(B) Hexagonal
(C) Orthorhombic
(D) Cubic

Answer: Option D

Q 57. Low resistivity materials are used in

(A) Transformer, motor and generator windings
(B) Transmission and distribution lines
(C) House wiring
(D) All above applications

Answer: Option D

Q 58. Effect of moisture on the insulating materials is to

(A) Decrease dielectric constant
(B) Decrease dielectric strength
(C) Decrease insulation resistance
(D) All of the above

Answer: Option D

Q 59. For germanium the forbidden energy gap is

(A) 0.15 eV
(B) 0.25 eV
(C) 0.5 eV
(D) 0.7 eV

Answer: Option D

Q 60. Selenium is ________ semiconductor.

(A) Extrinsic
(B) Intrinsic
(C) N-type
(D) P-type

Answer: Option B