Page 869 - Basic Electrical Engineering

voltmeter.

[Ans R = 99,900 Ω]
m

43. A PMMC-type instrument gives a full-scale deflection of 100 mA when a potential difference
across the terminal is 1 V. How can this instrument be used to measure upto 100 V?

[Ans Connecting a series resistance of 990 Ω]

C. Multiple Choice Questions

1. 1. For measurement of direct current we may use

a. a moving-iron-type ammeter
b. a galvanometer
c. a permanent-magnet moving-coil-type ammeter
d. a hot-wire-type ammeter.

2. In permanent-magnet wiring-coil-type instruments expression for deflecting torque can be
written as

a. T α I 2
d
b. T αI
d

c.

d. .

3. Damping of deflecting-type instruments is done to

a. reduce the oscillations of the pointer in the final deflected position
b. make the moving system go slow
c. make the moving system move fast
d. reduce the angle of deflection of the pointer on the graduated acate.

4. For which of the following instruments the calibrated scale is linear?

a. Repulsion-type moving-iron instruments
b. Attraction-type moving-iron instruments
c. Permanent-magnet moving-coil instruments
d. Dynamometer-type instruments.