Ammeters And Voltmeters Theory - 1 - MCQs with answers

Ammeters And Voltmeters Theory - 1 - MCQs with answers

Q1. The instrument which can be used only with the d.c. supply is

A. PMMC instrument
B. Electrodynamometer instrument
C. Hot-wire instrument
D. Split phase induction type instrument

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Q2. The instrument which can be used only with the a.c. supply is/are

A. Induction type
B. Electrostatic type
C. Electrodynamometer type
D. All of these

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Q3. In a hot wire ammeter the current flowing through the resistance of 10Ω is given by

I = 3 + 2sin300t A

The measured value of current will be

A. 2.98 A
B. 3.31 A
C. 3.62 A
D. 4.01 A

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Q4. In a hot wire instrument, readings are

A. Dependent on frequency
B. Dependent on waveform
C. Dependent on both frequency and waveform
D. Independent of both frequency and waveform

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Q5. To convert a 2 mA meter with internal resistance of 120 ohm into an ammeter of range 0 – 200 mA, the value of shunt resistance required is

A. 1.121 ohm
B. 1.212 ohm
C. 1.312 ohm
D. 1.414 ohm

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Q6. If a moving iron instrument is to be used as ammeter then the coil has

A. Fewer number of turns of thin wire
B. Fewer number of turns of thick wire
C. Larger number of turns of thin wire
D. Larger number of turns of thick wire

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Q7. If the direction of current through the coil is upward, then the iron disc will be magnetized in such a way that it is

A. Pushed outwards
B. Pushed upwards
C. Pushed downwards
D. Pulled inwards

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Q8. A spring controlled moving iron voltmeter with full scale deflection of 150 V draws a current of 2 mA. What will be the meter reading if it draws a current of 1 mA?

A. 25.5 V
B. 27.5 V
C. 35.5 V
D. 37.5 V

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Q9. A repulsion type moving iron instrument when used with a.c. circuits, the deflecting torque is

A. Directly proportional to the rms current
B. Directly proportional to the square of rms current
C. Directly proportional to the peak current
D. Directly proportional to the square of the peak current

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Q10. What will a moving iron ammeter will read if a rectangular waveform current with peak value of 120 mA is passed through it?

A. 120 mA
B. 84.8 mA
C. 169.7 mA
D. 60 mA

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