Electrical and Electronics Measurement Mcq Pdf

21. The efficiency of an instrument is defined as the ratio of the measured quantity at full scale to the power taken by the instrument at

(a) one-fourth scale.
(c) three-fourth scale.
(b) half scale.
(d) full scale.

22. Dead time of the instrument is

(a) the time required by an instrument to begin to respond to a change in the measurand.
(b) the time required by an instrument to warm up initially.
(c) the largest change of input quantity for which there is no output of the instrument.
(d) none of the above.

23. Dead zone of an instrument is

(a) the time required by an instrument to warm up initially.
(b) the largest change of input quantity for which there is no output of the instrument.
(c) the time required by an instrument to begin to respond to a change in measurand.
(d) the unmeasured quantity which exceeds the maximum range of the instrument.
(e) none of the above.

24. Torque/weight ratio of an instrument indicates

(a) selectivity.
(b) accuracy.
(c) fidelity
(d) sensitivity.

25. Which of the following statements is true for a measuring instrument ?

(a) If it is precise, it is accurate.
(b) If it is linear, it is sensitive.
(c) If it has a digital display, it is accurate.
(d) If it uses null balance technique, it has a high input impedance.

26. A first order instrument is characterized by

(a) time constant only.
(b) static sensitivity and time constant.
(c) static sensitivity and damping coefficient.
(d) static sensitivity, damping coefficient and natural frequency of oscillations.

27. An indicating instrument is more sensitive if its torque to weight ratio is

(a) much larger than unity.
(b) of the order of unity.
(c) much less than unity.
(d) made deflection dependent.

28. Which one of the following decides the time of response of an indicating instrument ?

(a) Deflecting system.
(b) Controlling system.
(c) Damping system.
(d) Pivot and jewel bearings.

29. The difference between the indicated value and the true value of a quantity is

(a) gross error.
(b) absolute error.
(c) dynamic error.
(d) relative error.

30. The errors introduced by an instrument fall in which category ?

(a) Systematic errors.
(b) Random errors.
(c) Gross errors.
(d) Environmental errors.

31. To measure 5 volts, if one selects a 0 – 100 V range voltmeter which is accurate within ±1%, then the error in this measurement may be up to

(a) ±1.5%
(b) ±2.5%
(c) ±7.5%
(d) ±20%

32. A 0 – 100 V voltmeter has an accuracy of 1 per cent at full-scale reading. What will be the error if it reads 50 V?

(a) 1 per cent.
(b) 2 per cent.
(c) 0.5 per cent.
(d) 4 per cent.

33. A 0 – 250 V voltmeter has a guaranteed accuracy of 2 per cent of full-scale reading. The voltage measured by this voltmeter is 150 volts. The limiting error in percentage is

(a) 2.5%
(b) 0.05%
(c) 3.33%
(d) 5.0%

34. A 0 – 25 Amp ammeter has a guaranteed accuracy of 1 per cent of full-scale reading. The current measured by this ammeter is 10 Amp. The limiting error in percentage for this instrument is

(a) 2.5%
(b) 0.5%
(c) 0.25%
(d) 0.025%

35. A 0 to 300 V voltmeter has an error of ±2% of full scale deflection. What is the range of readings if true voltage is 30 V?

(a) 24 V – 36 V
(b) 20 V – 40 V
(c) 29.4 V – 30.6 V
(d) 20 V – 30 V

36. The pressure in a tank varies from 20 psi to 100 psi. Further pressure in the tank is desired to be kept at 50 psi. The full-scale error when pressure inside the tank is 30 psi, is given by

(a) – 62.5%
(b) 25%
(c) 80%
(d) – 2.5%

37. The measured value of a capacitor is 205.5 pF whereas its true value is 202.4 pF The relative error is

(a) 1.87%
(b) 1.94%
(c) 1.53%
(d) 1.73%

38. A standard cell of 1.085 volts used with a simple potentiometer balances at 50 cm. The percentage error in the voltmeter which balances at 60 cm when reading 1.2 V is

(a) 1.8 % low.
(b) 3.6 % low.
(c) 1.8 % high.
(d) 3.6 % high.

39. A 150 V moving iron voltmeter of accuracy class 1.0 reads 75 V when used in a circuit under standard conditions. The maximum possible percentage error in the reading is

(a) 0.5.
(b) 1.0.
(c) 2.0.
(d) 4.0.

40. A thermometer is calibrated from 150° to 200°C. The accuracy specified is ± 0.25%. The maximum static error in measurement is

(a) ± 0.5°C.
(b) 0.375°C.
(c) ± 0.125°C.
(d) ± 0.0125°C.