Electrical and Electronics Measurement Mcq Questions

23. Which of the following units are present in a spectrum analyzer?

1. Mixer. 2. Sawtooth generator. 3. Local oscillator.
Select the correct answer using the codes given below: Codes:
(a) 1, 2 and 3.
(b) 1 and 2.
(c) 1 and 3.
(d) 2 and 3.

24. The harmonic distortion percentage is accurately measured by

(a) VTVM.
(b) CRO.
(c) harmonic distortion analyzer.
(d) VOM.

25. Which of the following
instruments are useful in measuring the signal levels of individual harmonics in an unknown waveform?

1. Distortion analyzer
2. Wave analyzer
3. Spectrum analyzer

Select the correct answer using the codes given below: Codes :
(a) 1 and 2.
(b) 2 and 3.
(c) 1 and 3.
(d) 1, 2 and 3.

26. The highly selective fixed frequency filters are used in a

(a) resonant wave analyzer.
(b) heterodyne wave analyzer.
(c) distortion analyzer.
(d) Q-meter.

27. The study of energy distribution across the frequency spectrum of a given electrical signal is done by a

(a) distortion meter.
(b) wave analyzer.
(c) spectrum analyzer.
(d) Q-meter.

28. Which of the following electronic instruments (or equipment) can be used to measure correctly the fundamental frequency component of a waveform and its higher harmonics ?

1. CRO.
2. VTVM.
3. Spectrum analyzer.
4. Distortion factor meter.

Select the correct answer from the codes given below:
(a) 1 and 2.
(b) 2 and 3.
(c) 3 and 4.
(d) 1 and 4.

29. Consider the following statements:

1. The main drawback of digital system is that the real world is mainly analog.
2. The major advantage of digital instruments over analog instruments is higher accuracy and better resolution.
3. Digital instruments are ordinarily used for the measurement of both analog and digital quantities.

Which of the above statements is/are correct?
(a) 1, 2 and 3.
(b) 1 and 3 only.
(c) 2 only.
(d) 1 and 2 only.

30. A DVM measures

(a) peak value.
(b) rms value.
(c) peak-to-peak value.
(d) average value.

31. Accuracy of DVM is specified as

(a) percentage of the actual reading.
(b) percentage of the full-scale reading.
(c) number of least significant digits.
(d) all of these.

32. The following statements are related to a DVM. Which of them is true ?

(a) Common mode rejection is the same for ac and dc voltages.
(b) Its accuracy depends on source impedance.
(c) It does not have series mode error.
(d) Use of shunts for dc current measurements increases its accuracy.

33. The circuit generally used in digital instruments to convert sine waves into rectangular pulses is a

(a) sawtooth generator.
(b) differential amplifier.
(c) sample and hold circuit.
(d) Schmitt trigger.

34. Integrating principle in the digital measurement is the conversion of

(a) voltage to time.
(b) voltage to frequency.
(c) voltage to current.
(d) current to voltage.

35. Which one of the following decides the precision of integrating digital voltmeter?

(a) Reference voltage of analog comparator.
(b) Slope of the generated ramp.
(c) Width of the generated pulses.
(d) Electronic counter.

36. Which one of the following is not true of digital instruments ?

(a) Loading of the circuit under measurement is less.
(b) Accuracy is better.
(c) Free from observational errors.
(d) Can present the reading in overall context of range.

37. The conversion of a voltage value to a time interval is carried out by comparing the unknown voltage with a voltage ramp in a

(a) ramp type DVM.
(b) integrating type DVM.
(c) continuous type DVM.
(d) successive approximation type DVM.

38. An integrating DVM measures

(a) peak value of input voltage.
(b) rms value of input voltage.
(c) true average of the input voltage.
(d) variance of the input voltage.

39. Consider the following elements :

1. Buffer. 2. Differentiator. 3. Integrator. 4. Comparator.

Which of the above is/are components in a dual slope integrating type voltmeter ?
(a) 1, 3 and 4.
(b) 1 and 2.
(c) 3 and 4.
(d) 2 only.

40. Consider the following statements: The A to D converter used in a digital instrument could be

1. Successive approximation converter type.
2. Flash converter type.
3. Dual slope converter type.

The correct sequence in the increasing order of the conversion time taken by these types is
(a) 1, 2 and 3.
(b) 2, 1 and 3.
(c) 1, 3 and 2.
(d) 2, 3 and 1.

41. The precision of a ramp type digital voltmeter depends on

(a) frequency of the generator and slope of the ramp.
(b) frequency of the generator.
(c) slope of the ramp.
(d) switching time of the gate.

42. Which one of the following digital voltmeters is most suitable to eliminate the effect of period noise ?

(a) ramp type digital voltmeter.
(b) integrating type digital voltmeter.
(c) successive approximation type digital voltmeter.
(d) servo type digital voltmeter.

43. A DVM has

(a) no auto ranging facility and no overload protection.
(b) a resolution of 1 part in 10⁶.
(c) an input resistance of 1 MΩ and an input capacitance of 1µF
(d) an accuracy of about ± 2%.

44. To eliminate 50 Hz pick-up in a dual slope DVM, the minimum period of integration of the input signal is

(a) 1 ms
(b) 20 ms
(c) 1 s
(d) 100 s

45. An average-reading digital multimeter reads 10 V when fed with a triangular wave, symmetric about the time-axis. For the same input an rms-reading meter will read

(a) 20/√3
(b) 10/√3
(c) 20√3
(d) 10√3

46. What is the range for a 3 – 1/2 digit digital voltmeter ?

(a) 0 to 1999
(b) 0 to 1500
(c) 0 to 999
(d) 0 to 19999

47. In a digital voltmeter, the oscillator frequency is 400 kHz. The ramp voltage falls from 8 V to 0 V in 20 ms. What is number of pulses counted by the counter?

(a) 8,000
(b) 4,000
(c) 3,200
(d) 1,600

48. In a digital voltmeter, ‘over-ranging’ implies that

(a) the next four digits are switched-on.
(b) 1/2 digit is switched off.
(c) 1/2 digit is switched on.
(d) an over-range indicator starts glowing.

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