Current Electricity

11. A rheostat differs from potentiometer in the respect that it

1. has lower wattage rating
2. has higher wattage rating
3. has large number of turns
4. offers large number of tapping

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12. A substance whose molecules consist of dissimilar atoms is called

1. semi-conductor
2. super-conducto
3. compound
4. insulator

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13. A thermistor has

1. positive temperature coefficient
2. negative temperature coefficient
3. zero temperature coefficient
4. variable temperature coefficient

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14. All good conductors have high

1. conductance
2. resistance
3. reluctance
4. thermal conductivity

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15. All of the following are equivalent to watt except

1. (amperes) ohm
2. joules/sec.
3. amperes x volts
4. amperes/volt

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16. An electric filament bulb can be worked from

1. D.C. supply only
2. A.C. supply only
3. Battery supply only
4. All above

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17. An instrument which detects electric current is known as

1. voltmeter
2. rheostat
3. wattmeter
4. galvanometer

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18. An open resistor, when checked with an ohm-meter reads

1. zero
2. infinite
3. high but within tolerance
4. low but not zero

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19. are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators.

1. Varistors
2. Thermistor
3. Semi-conductors
4. Variable resistors

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20. Bulbs in street lighting are all connected in

1. parallel
2. series
3. series-parallel
4. end-to-end

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