Electrical Measurements & Units Test Questions - Set 1

1)   Instruments are subdivided into active and passive based on whether the output of instrument is produced by the quantity being measured simply changes the magnitude of some external power source. The pressure measuring device and the float-type petrol tank level indicator are example of

a. Active instruments
b. Passive instruments
c. Former is active instrument and later is passive instrument
d. Former is passive instrument and later is active instrument
Answer  Explanation 

ANSWER: Former is passive instrument and later is active instrument

Explanation:
No explanation is available for this question!


2)   Considering cost of instruments, which is a better choice, active or passive?

a. Active instruments
b. Passive instruments
c. Cost of both active and passive instruments are approximately same
d. None of these
Answer  Explanation 

ANSWER: Passive instruments

Explanation:
No explanation is available for this question!


3)   In deadweight gauge, weights are added on the top of piston until the piston reaches a datum level. The datum level is known as

a. Null point, where the downward force balances the fluid pressure
b. Lowest point of the container
c. Highest level of fluid in the container
d. None of these
Answer  Explanation 

ANSWER: Null point, where the downward force balances the fluid pressure

Explanation:
No explanation is available for this question!


4)   The accuracy of the deflection type instruments and of the null type instruments depends on

a. Linearity, calibration of spring
b. Calibration of spring, linearity and calibration of weights
c. Linearity and calibration of spring, calibration of weights
d. Both depends on calibration of weight
Answer  Explanation 

ANSWER: Linearity and calibration of spring, calibration of weights

Explanation:
No explanation is available for this question!


5)   In terms of usage, deflection type instruments are

a. More convenient than null type instrument
b. Less convenient than null type instruments
c. Both are equally convenient
d. None of these
Answer  Explanation 

ANSWER: More convenient than null type instrument

Explanation:
No explanation is available for this question!


6)   The output of an analogue instrument varies

a. Continuously and can have an infinite number of values within its range of instruments
b. In discrete steps and can have an infinite number of values within its range of instruments
c. Continuously and can have an finite number of values within its range of instruments
d. In discrete steps and can have an infinite number of values within its range of instruments
Answer  Explanation 

ANSWER: Continuously and can have an infinite number of values within its range of instruments

Explanation:
No explanation is available for this question!


7)   The microcomputer performs its computations in

a. Analogue form
b. Digital form
c. Either analogue form or digital form depending on their applications
d. None of these
Answer  Explanation 

ANSWER: Digital form

Explanation:
No explanation is available for this question!


8)   To read and record a measurement, the indicating type instrument

a. Always requires human intervention
b. Does not requires human intervention
c. Requires human intervention only when the instrument consists of a rotating pointer moving against a scale
d. Requires human intervention only when the instrument consists of a rotating scale moving against a pointer
Answer  Explanation 

ANSWER: Always requires human intervention

Explanation:
No explanation is available for this question!


9)   Accuracy of an measuring instrument indicates the

a. Closeness of the output reading to the true value
b. Ratio of output value to the input value
c. Change in output with each change in input
d. Degree of freedom from random errors
Answer  Explanation 

ANSWER: Closeness of the output reading to the true value

Explanation:
No explanation is available for this question!


10)   If a pressure gauge of range 0-10 bar has a quoted inaccuracy of ±1.0 % of full scale reading, then it means

a. Minimum expected error in any reading is 0.1 bar
b. Maximum expected error in any reading is 0.1 bar
c. Maximum expected error in any reading is 1 bar
d. Minimum expected error in any reading is 1 bar
Answer  Explanation 

ANSWER: Maximum expected error in any reading is 0.1 bar

Explanation:
No explanation is available for this question!


11)   An instrument with a range of 0-10 bar is used for measuring pressure. If the expected value of reading is between 0 and 1 bar then the instrument will give

a. More accurate readings than the instrument with range of 0-5 bar
b. Less accurate readings than the instrument with range of 0-5 bar
c. Accuracy of reading will be same for both the instruments with range of 0-10 bar and 0-5 bar
d. None of these
Answer  Explanation 

ANSWER: Less accurate readings than the instrument with range of 0-5 bar

Explanation:
No explanation is available for this question!


12)   A voltmeter connected across a resistor gives a value of 65 V but the expected value of resistor was 68 V. Then the absolute error and the relative accuracy of the measurement will be

a. 3.2%, 96.8%
b. 3.8%, 96.2%
c. 4%, 96%
d. 4.4%, 95.59%
Answer  Explanation 

ANSWER: 4.4%, 95.59%

Explanation:
No explanation is available for this question!


13)   Precision of an instrument is defined as

a. Closeness of output to the true value
b. Change in output for every change in input
c. Degree of freedom from random errors
d. Both (a) and (b)
Answer  Explanation 

ANSWER: Degree of freedom from random errors

Explanation:
No explanation is available for this question!


14)   An instrument with high precision implies

a. High accuracy
b. Low accuracy
c. Does not imply anything about measurement accuracy
d. None of these
Answer  Explanation 

ANSWER: Does not imply anything about measurement accuracy

Explanation:
No explanation is available for this question!


15)   Low accuracy measurements from a high precision instrument are normally caused by

a. Bias in the measurement
b. Human errors
c. Instrumental defect
d. Low temperature
Answer  Explanation 

ANSWER: Bias in the measurement

Explanation:
No explanation is available for this question!


16)   Which of the following statements are correct I. Repeatability means the closeness of output readings when the same input is applied repetitively over a short period of time, with the same measurement conditions and same instruments. II. Reproducibility means the closeness of output readings for the same input when there are changes in the method of measurement and conditions of measurement.

a. Both I and II are correct
b. Only I is correct
c. Only II is correct
d. Both are incorrect
Answer  Explanation 

ANSWER: Both I and II are correct

Explanation:
No explanation is available for this question!


17)   For an instrument the degree of repeatability or reproducibility in measurements is an alternative way of expressing its

a. Precision
b. Accuracy
c. Sensitivity
d. Linearity
Answer  Explanation 

ANSWER: Precision

Explanation:
No explanation is available for this question!


18)   Range or span of an instrument defines

a. Minimum value of quantity that the instrument is designed to measure
b. Maximum value of quantity that the instrument is designed to measure
c. Both minimum and maximum value of quantity that the instrument is designed to measure
d. None of these
Answer  Explanation 

ANSWER: Both minimum and maximum value of quantity that the instrument is designed to measure

Explanation:
No explanation is available for this question!


19)   A voltmeter of 0 to 250 V has an error of ± 1% of full scale deflection. If the true voltage of voltmeter is 25 V then the range of its reading is

a. 22.5 V – 27.5 V
b. 27.5 V – 29.5 V
c. 24 V – 26 V
d. 25.5 V – 26.5 V
Answer  Explanation 

ANSWER: 22.5 V – 27.5 V

Explanation:
No explanation is available for this question!


20)   Four observers recorded a set of current measurement as: 125.09 mA, 125.21 mA, 125.05 mA, 125.14 mA. The range or span of error will be

a. ± 0.02 mA
b. ± 0.06 mA
c. ± 0.08 mA
d. ± 1.02 mA
Answer  Explanation 

ANSWER: ± 0.08 mA

Explanation:
No explanation is available for this question!