Electrical and Electronics Measurement Mcq Pdf

41. A. Wheatstone bridge requires a change of 6 Ω in the unknown arm of the bridge to produce a change in deflection of 3 mm of the galvanometer. The sensitivity of the instrument is

(a) 0.5%
(b) 2%
(c) 0.5 mm /Ω
(d) 2 Ω/mm

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42. Threshold of sensitivity in reference to instruments is

(a) the smallest signal that causes detectable output.
(b) the largest signal which can be measured.
(c) the value of sensitivity on the highest scale.
(d) the value of sensitivity on the lowest scale.

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43. Sensitivity in accuracy of a recording instrument means the

(a) degree to which the instrument is not sensitive enough to repeat readings.
(b) maximum error in sensitivity displayed by a pen.
(c) smallest signal required to give detectable output.
(d) amount of input needed to give unit pen deflection.

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44. Sensitivity of a voltmeter is given as

(a) Ω/V
(b) reciprocal of full-scale deflection current.
(c) both (a) and (b).
(d) none of these.

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45. Accuracy is defined as the

(a) measure of the consistency or reproducibility of the measurement.
(b) closeness with which an instrument reading approaches the true value of the quantity being measured.
(c) smallest measurable input change.
(d) ratio of the change in output signal of an instrument to a change in the input.

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46. The degree of reproducibility among several independent measurements of same true value under reference conditions is known as

(a) accuracy.
(b) precision.
(c) linearity.
(d) calibration.

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47. Which one of the following statements is not correct ?

(a) It is not possible to have precise measurements which are not accurate.
(b) Correctness in measurements requires both accuracy and precision.
(c) Reproducibility and consistency are expressions that best describe precision in measurements.
(d) An instrument with 2% accuracy is better than another with 5% accuracy.

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48. A resistance of 105 ohms is specified using significant figures as indicated below :

  1. 105 ohms
  2. 105.0 ohms
  3. 0.000105 MΩ

Among these
(a) 1 represents greater precision than 2 and 3.
(b) 2 represents greater precision but 1 and 3 represent same precision.
(c) 2 and 3 represent greater precision than 1.
(d) 1, 2 and 3 represent same precision.

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49. A resistance of 108 Ω is specified using significant figures as indicated below:

  1. 108 Ω
  2. 108.0 Ω
  3. 0.000108 MΩ

Among these
(a) 1 represents greater precision than 2 and 3.
(b) 2 represents greater precision but 1 and 3 represent same precision.
(c) 2 and 3 represent greater precision than 1.
(d) 1, 2 and 3 represent the same precision.

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50. The value of a quantity and its uncertainty are given as 26455 ± 3754 without rounding off. Only two significant digits are relevant for error. Value of error rounded off to two significant figures is

(a) 26500 ± 3800
(b) 26400 ± 3800
(c) 26460 ± 3750
(d) 26400 ± 3700

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51. Which one of the following statements is correct ? The application of the instrument in wrong manner in the procedure of measurement results in a/an

(a) systematic error.
(b) random error.
(c) gross error.
(d) instrument error.

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52. What are the causes of gross error in the instruments?

  1. Misreading of instruments.
  2. Incorrect adjustment of instruments.
  3. Errors due to defective instrument.
  4. Errors due to effect of environment on the instrument.

(a) 1 and 2.
(b) 2 and 3.
(c) 3 and 1.
(d) 2 and 1.

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53. Systematic errors are

(a) instrumental errors.
(b) environmental errors.
(c) observational errors.
(d) all of the above.

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54. Consider the following:

  1. Human errors.
  2. Improper application of instruments.
  3. Error due to worn parts of an instrument.
  4. Errors due to effects of environment.

Which of the above come under the type of systematic errors?
(a) 1 and 2.
(b) 2 and 3.
(c) 3 and 4.
(d) 1 and 4.

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55. Which of the following types of errors come under systematic errors?

  1. Irregular spring tension.
  2. Improper readings of an instrument.
  3. Loading effects.
  4. Error due to the presence of electric field or magnetic field.

(a) 1 and 2.
(b) 2 and 3.
(c) 3 and 1.
(d) 4 and 1.

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56. Which one of the following statements correctly represents the systematic error ?

(a) These errors can be calculated from the details of the instruments.
(b) These are the residual errors.
(c) These errors may occur under controlled conditions.
(d) These are the errors committed by the experimenters.

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57. A set of observations has a wide range so it has

(a) low accuracy.
(b) low precision.
(c) high accuracy but low precision.
(d) high precision but low accuracy.

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58. Two capacitances, C1 = 150 ± 2.4 µF and C2 = 120 ± 1.5 µF are connected in parallel. What is the limiting error of the resultant capacitance C ?

(a) 0.9 µF
(b) 1.95 µF
(c) 3.9 µF
(d) 4.8 µF

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59. A zero mean random signal is uniformly distributed between limits -a and +a and its mean square value is equal to its variance. Then the rms value of the signal is

(a) a÷√3
(b) a÷√2
(c) a√2
(d) a√3

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60. The voltage of a standard cell is monitored daily over a period of one year. The mean value of voltage for every month shows a standard deviation of 0.1 mV. The standard deviation of the set constituted by the monthly mean values will be

(a) zero
(b) 0.1/12
(c) 0.1/√12
(d) 0.1

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