Current Electricity

61. The number of electrons in the outer most orbit of carbon atom is

1. 3
2. 4
3. 6
4. 7

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62. The property of a conductor due to which it passes current is called

1. resistance
2. reluctance
3. conductance
4. inductance

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63. The rating of a fuse wire is always expressed in

1. ampere-hours
2. ampere-volts
3. kWh
4. amperes

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64. The ratio of mass of proton to that of electron is nearly (a) 1840

1. 1840
2. 1840
3. 30
4. 4

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65. The resistance of a conductor varies inversely as

1. length
2. area of cross-section
3. temperature
4. resistivity

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66. The resistance of a copper wire 200 m long is 21 Q. If its thickness (diameter) is 0.44 mm, its specific resistance is around

1. 1.2 x 10∼8 Q-m
2. 1.4 x 10∼8 Q-m
3. 1.6 x 10"”8 Q-m
4. 1.8 x 10"8 Q-m

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67. The resistance of a few meters of wire conductor in closed electrical circuit is

1. practically zero
2. low
3. high
4. very high

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68. The resistance of a parallel circuit consisting of two branches is 12 ohms. If the resistance of one branch is 18 ohms, what is the resistance of the other?

1. 18 Q
2. 36 Q
3. 48 Q
4. 64 Q

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69. The S.I. unit of power is

1. Henry
2. coulomb
3. watt
4. watt-hour

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70. The substances which have a large number of free electrons and offer a low resistance are called

1. insulators
2. inductors
3. semi-conductors
4. conductors

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