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

Correct answer: (B)
has higher wattage rating

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

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

Correct answer: (C)
compound

13. A thermistor has

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

Correct answer: (C)
zero temperature coefficient

14. All good conductors have high

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

Correct answer: (A)
conductance

15. All of the following are equivalent to watt except

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

Correct answer: (D)
amperes/volt

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

Correct answer: (D)
All above

17. An instrument which detects electric current is known as

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

Correct answer: (D)
galvanometer

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

Correct answer: (B)
infinite

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

Correct answer: (C)
Semi-conductors

20. Bulbs in street lighting are all connected in

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

Correct answer: (A)
parallel

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