Voltmeter MCQ

31. The advantage of using a dual slope ADC in a digital voltmeter is that

  1. Its conversion time is small
  2. Its accuracy is high
  3. It gives output in BCD format
  4. None of these
Answer. b

32. DC probes are generally used with a voltmeter to

  1. Decrease its range
  2. Increase its range
  3. Frequency independent
  4. None of these
Answer. a

33. A DC voltage has a sensitivity of 1000 ohm/V. When it measured half and Full-scale in 100 V range: the current through the voltmeter is

  1. 100 mA
  2. 1 mA
  3. 0.5 mA
  4. 50 mA
Answer. c

34. The scale of a voltmeter is uniform. Its type is

  1. Moving iron
  2. Induction
  3. Moving coil permanent magnet
  4. Moving coil dynamometer
Answer. c

35. Two voltmeters have the same range 0-400 V. The internal impedances are 30 kΩ and 20 kΩ. If they are connected in series and 600 V be applied across them, the readings are

  1. 360V and 240V
  2. 300V each
  3. 400 V and 200V
  4. Out of range for one of the meters and 100 V for the other
Answer. a

36. Electrostatic type instruments are primarily used as

  1. Ammeters
  2. Wattmeters
  3. Voltmeters
  4. ohmmeters
Answer. c

37. A spring controlled moving iron voltmeter draws a current of 1 mA for full-scale value of 100 V. If it draws a current of 0.5 mA, what is the meter reading?

  1. 25 V
  2. 50 V
  3. 100 V
  4. 300 V
Answer. a

38. The capacitance of 0—1000 V electrostatic voltmeter increases from 36 to 42 pf from zero to full-scale deflection. It is required to extend the range of voltmeter to 10000 V by using an external series capacitor. What should be the value of the series capacitor?

  1. 0.8 pf
  2. 1.00 pf
  3. 6.644 pf
  4. 4.667 pf
Answer. d

39. An ammeter is convertible to a voltmeter by

  1. Changing the scale
  2. Putting a large resistance in parallel with the actual measuring part of the instrument
  3. Putting large resistance in series with the actual measuring part of the instrument
  4. Simply installing the instrument in parallel with the current
Answer. c

40. A zero to 300 V voltmeter has an error of 12% on full-scale deflection. If the true voltage is 30 V then the range of readings on this voltmeter will be

  1. 20 to 40 V
  2. 26.4 to 33.6 V
  3. 29.4 to 30.6 V
  4. 24 to 36 V
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