# Indicating Instruments MCQ Questions & Answers

Indicating Instruments MCQs : This section focuses on the "Indicating Instruments". These Multiple Choice Questions (MCQs) should be practiced to improve the Indicating Instruments skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

A 10 mA PMMC ammeter reads 4 mA in a circuit. Its bottom control spring snaps suddenly. The meter will now show __________

A. 10 mA
B. 8 mA
C. 2 mA
D. Zero

Question 2

A current of  8 + 6$$\sqrt{2}$$ (sin (?t + 30°)) A is passed through three meters. The respective readings (in ampere) will be?

A. 8, 6 and 10
B. 8, 6 and 8
C.  8, 10 and 10
D. -8, 2 and 2

Question 3

A current of [2 + $$\sqrt{2}$$ sin (314t + 30) + 2$$\sqrt{2}$$ cos (952t +45)] is measured with a thermocouple type, 5A full scale, class 1 meter. The meter reading would lie in the range?

A. 5 A ± 1 %
B. (2 + 3$$\sqrt{2}$$) A ± 1%
C. 3 A ± 1.7 %
D. 2 A ± 2.5 %

Question 4

A meter has a full scale of 90° at a current of 1 A. This meter has a perfect square law response. What is the current when the deflection angle is 45°?

A. 0.5 A
B. 0.25 A
C. 0.707 A
D. 0.67 A

Question 5

A moving coil of a meter has 250 turns and a length and depth of 40 mm and 30 mm respectively. It is positioned in a uniform radial flux density of 450 mT. The coil carries a current of 160 mA. The torque on the coil is?

A. 0.0216 N-m
B. 0.0456 N-m
C. 0.1448 N-m
D. 1 N-m

Question 6

A moving iron ammeter produces a full-scale torque of 240 ?N-m with a deflection of 120° at a current of 10 A. the rate of change of self-inductance (?H/rad) of the instrument at full scale is?

Question 7

A PMMC rated as 100 ?A is used in a rectifier type of instrument which uses full wave rectification. What is the sensitivity on sinusoidal AC?

A. 4.5 k?/V
B. 18 k?/V
C. 10 k?/V
D. 9 k?/V

Question 8

A rectifier type AC voltmeter consists of a series resistance R, an ideal full-wave rectifier bridge and a PMMC instrument. The internal resistance of the instrument is 100 ? and a full- scale deflection is produced by a DC current of 1 mA. A voltage of 100 V (rms) is applied to the input terminals. The value of R required is?

A. 63.56 ?
B. 89.83 ?
C. 89.83 k?
D. 141.3 k?

Question 9

In a moving iron meter, the deflection torque is proportional to?

A. Square of the current through the coil
B. Current through the coil
C. Sine of measurand
D. The Square root of the measurand

Question 10

Moving Iron Instrument can be used as ____________

A. An ammeter for measuring DC as well as AC
B. For measuring DC current and voltages only
C. An ammeter and a voltmeter for measuring DC as well as AC
D. For measuring AC current and voltages only

Question 11

The discharge of a capacitor through a ballistic galvanometer produces a damped frequency of 0.125 Hz and successive swings of 120, 96 and 76.8 mm. The damping ratio is?

A. 0.0568
B. 0.0887
C. 0.0357
D. 0.0441

Question 12

The discharge of a capacitor through a ballistic galvanometer produces a damped frequency of 0.125 Hz and successive swings of 120, 96 and 76.8 mm. The logarithmic decrement is?

A. 0.225
B. 0.565
C. 0.484
D. 0.7887

Question 13

The full-scale deflection current of a meter is 4 mA and its internal resistance is 400?. This meter is to have full deflection when 400 V is measured. What is the value of the series resistor to be used?

A. 99.90 k?
B. 100 k?
C. 99.60 k?
D. 100 ?

Question 14

The full-scale deflection current of an ammeter is 4 mA and its internal resistance is 400?. If this meter is to have a full deflection of 10 A, what is the value of the shunt resistance to be used?

A. 49.99 ?
B. 0.16 ?
C. 1.5 ?
D. 2.6 ?

Question 15

The scale of a dynamometer type instrument marked in terms of RMS value would be__________

A. Uniform throughout
B. Non-uniform and crowded near the full scale
C. Non-uniform and crowded at the beginning
D. Non-uniform and crowded around mid-scale

Question 16

The standardization of AC potentiometer is done by ____________

A. Using a DC standard source and d Arsonval galvanometer
B. Using AC standard sources and transfer instruments
C. Using a standard AC voltage source
D. Using a DC standard source and transfer instruments

Question 17

Two 100 ?A full-scale PMMC meters are employed to construct a 10 V and a 100 V full-scale voltmeter. These meters will have figure of merit (sensitivities) as?

A. 10 k?/V and 10 k?/V
B. 100 k?/V and 10 k?/V
C. 10 k?/V and 100 k?/V
D. 10 k?/V and 1 k?/V

Question 18

Two ammeters, one with a full-scale current of 1 mA and internal resistance of 100 ? and other a full-scale current of 10 mA and internal resistance of 25 ? are in parallel. What is the total current, these two meters can carry without the reading out of scale in any meter?

A. 1 mA
B. 10 mA
C. 11 mA
D. 5 mA

Question 19

A PMMC rated as 100 μA is used in a rectifier type of instrument which uses full wave rectification. What is the sensitivity on sinusoidal AC?

A. 4.5 kΩ/V
B. 18 kΩ/V
C. 10 kΩ/V
D. 9 kΩ/V

Question 20

A rectifier type AC voltmeter consists of a series resistance R, an ideal full-wave rectifier bridge and a PMMC instrument. The internal resistance of the instrument is 100 Ω and a full- scale deflection is produced by a DC current of 1 mA. A voltage of 100 V (rms) is applied to the input terminals. The value of R required is?

A. 63.56 Ω
B. 89.83 Ω
C. 89.83 kΩ
D. 141.3 kΩ

Question 21

The full-scale deflection current of a meter is 4 mA and its internal resistance is 400Ω. This meter is to have full deflection when 400 V is measured. What is the value of the series resistor to be used?

A. 99.90 kΩ
B. 100 kΩ
C. 99.60 kΩ
D. 100 Ω

Question 22

The full-scale deflection current of an ammeter is 4 mA and its internal resistance is 400Ω. If this meter is to have a full deflection of 10 A, what is the value of the shunt resistance to be used?

A. 49.99 Ω
B. 0.16 Ω
C. 1.5 Ω
D. 2.6 Ω

Question 23

The standardization of AC potentiometer is done by ____________

A. Using a DC standard source and d’ Arsonval galvanometer
B. Using AC standard sources and transfer instruments
C. Using a standard AC voltage source
D. Using a DC standard source and transfer instruments

Question 24

Two 100 μA full-scale PMMC meters are employed to construct a 10 V and a 100 V full-scale voltmeter. These meters will have figure of merit (sensitivities) as?

A. 10 kΩ/V and 10 kΩ/V
B. 100 kΩ/V and 10 kΩ/V
C. 10 kΩ/V and 100 kΩ/V
D. 10 kΩ/V and 1 kΩ/V