MCQs of Alternating Current

Showing 81 to 90 out of 168 Questions

81.

In an a.c. circuit, the current is given by

i = 5 \sin (100 t - \frac{π}{2})

and the a.c. potential is V = 200 sin (100t) volt. Then what is the power consumption ?

82.

In an a.c. circuit with voltage V and current I, what is the power dissipated ?

(a)	VI
(b)	$\frac{1}{2} VI$
(c)	$\frac{1}{\sqrt{2}} VI$
(d)	Depend on the phase difference between V and I.

83.

In the transmission of a.c. power through transmission lines, when the voltage is stepped up n times, the power loss in transmission _____

84.

A bulb is connected first with D.C. and then A.C. of same voltage, it will shine brightly with _____

85.

The frequency of an alternating voltage is 50 cycles/s and its amplitude is 120 V. Then what is the rms value of voltage ?

86.

Voltage and current in an a.c. circuit are given by

V = 5 \sin (100 πt - \frac{π}{6})

and

I = 4 \sin (100 πt + \frac{π}{6})

then _____

87.

A lamp consumes only 50% of maximum power in an a.c. circuit. What is the phase difference between the applied voltage and the circuit current ?

88.

The instantaneous value of current in an A.C. circuit is

I = 2 \sin (100 πt + \frac{π}{3})

A. The current will be maximum for the first time at _____ .

89.

The power factor of L-C-R circuit at resonance is _____

90.

What is the power factor of a good choke coil ?

Showing 81 to 90 out of 168 Questions