Basic Concept of Electricity MCQs

Question 1

A sine wave has a frequency of 50 Hz. Its angular frequency will be

Accepted Answer

100 radians/sec

Answer

50 radians/sec

Answer

50 n radians/sec

Answer

100 n radians/sec

Question 2

The time period of an alternating quantity is 0.02 second. Its frequency will be

Accepted Answer

50 Hz

Answer

25 Hz

Answer

100 Hz

Answer

0.02 Hz

Question 3

In a multipolar (P-pole) machine runing at a speed of N rpm, the frequency of generated emf is equal to

Accepted Answer

120PN

Answer

?60PN

Answer

PN

Question 4

Average value of an unsymmetrical alterating quantity is calculated over the

Accepted Answer

whole cycle

Answer

half cycle

Answer

unsymmetrical part of the waveform

Answer

none of these

Question 5

A 50 Hz ac voltage is measured with a moving iron voltmeter and a rectifier type ac voltmeter connected in parallel. If the meter reading are VI and V2 respectively and the meters are free from calibration erros, then the form factor of the ac voltage may be estimated as

Accepted Answer

B w2U2

Answer

zero

Answer

?Bw2L/2

Answer

2Bw2L

Question 6

Form factor is the ratio of

Accepted Answer

rms value to average value

Answer

average value to rms value

Answer

peak value to average value

Answer

peak value to rms value

Question 7

Peak factor is the ratio of

Accepted Answer

peak value to rms value.

Answer

average value to rms value

Answer

rms value to average value

Answer

peak value to average value

Question 8

Form factor for dc supply voltage is always

Accepted Answer

unity

Answer

zero

Answer

infinity

Answer

any value between 0 and I.

Question 9

The two quantities are said to be in phase with each other when

Accepted Answer

both (a) or (b) above

Answer

the phase difference between two quantities is zero degree or radiad

Answer

each of them passes through zero values at the same instant and rises in the same direction

Answer

none of the above