Electrical Engineering Materials

61. The conductivity of a conductor can be increased by

1. decreasing its temperature
2. increasing its temperature
3. decreasing its vibration
4. increasing its vibration

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62. The conductivity of a metal is determined by

1. the electronic concentration and the mobility of the free electrons
2. the number of valence electrons per atom
3. either (a) or (b)
4. none of the above

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63. The conductivity of an extrinsic semiconductor with temperature

1. decreases
2. increases
3. remains constant
4. none of the above

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64. The conductors have transport phenomena of electrons due to

1. electric field
2. magnetic field
3. electromagnetic field
4. none of the above

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65. The converse of hardness is known as

1. malleability
2. toughness
3. softness
4. none of the above

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

1. 2
2. 4
3. 6
4. 8

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67. The covalent bond is formed by

1. transfer of electrons between atoms
2. sharing of electrons between atoms
3. sharing of variable number of electrons by a variable number of atoms
4. none of the above

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

1. equal to
2. less than
3. greater than
4. any of the above

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69. The forbidden gap in an insulator is

1. large
2. small
3. nil
4. any of the above

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70. The formula _________ determines the number of electrons that can be accommodated in any level.

1. 2n2
2. 4n2
3. 2n3
4. 4ns

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