MCQs of Alternating Current

Alternating Current MCQs

MCQs of Alternating Current

Showing 21 to 30 out of 168 Questions

21.

In an oscillating L-C circuit the maximum charge on the capacitor is Q. What will be the charge on the plate of the capacitor, when energy stored in magnetic field and electric field are equal ?

(a)	$\frac{Q}{3}$
(b)	$\frac{Q}{\sqrt{2}}$
(c)	Q
(d)	$\frac{Q}{2}$

22.

For L-C-R A.C. circuit resonance frequency is 600 Hz and frequencies at half power points are 550 Hz and 650 Hz. What will be the Q-factor ?

(a)	$\frac{1}{6}$
(b)	$\frac{1}{3}$
(c)	6
(d)	3

23.

An alternating voltage given as

V = 200 \sqrt{2} \sin 100 t

V is applied to a capacitor of

1 μF

. The current reading of the ammeter will be equal to _____ mA.

(a)	100
(b)	20
(c)	40
(d)	80

24.

The power in an A.C. circuit is given as

P = V_{r m s} I_{r m s} cosδ

. The power factor at the resonance frequency of a series L-C-R circuit will be _____ .

(a)	zero
(b)	1
(c)	$\frac{1}{2}$
(d)	$\frac{1}{\sqrt{2}}$

25.

If for an ideal step-up transformer, current in primary is I_p and current in secondary is I_s, their respective voltages are V_p and V_s, then

(a)	I_sV_s = I_pV_p
(b)	I_sV_s > I_pV_p
(c)	I_sV_s < I_pV_p
(d)	I_sV_p = I_pV_s

26.

On decreasing the angular frequency of A.C. source used in L - C -R series circuit, the capacitive reactance _____ and inductive resistance _____ .

(a)	increases, decreases
(b)	increases, increases
(c)	decreases, increases
(d)	decreases, decreases

27.

Current of

\frac{50}{π}

Hz frequency is passing through an A.C. circuit having series combination of resistance R = 100Ω and L = 1 H, then phase difference between voltage and current is _____ .

(a)	60°
(b)	45°
(c)	30°
(d)	90°

28.

If in an A.C. L-C series circuit X_L > C. Hence current _____

(a)	lags behind the voltage by $\frac{π}{2}$ in phase
(b)	lags the voltage by $\frac{π}{2}$ in phase
(c)	lags the voltage by Π in phase
(d)	lags behind the voltage by Π in phase

29.

in R-C circuit when charge on the plate of the capacitor is increasing, the energy obtain from the source is stored in _____ .

(a)	electric field
(b)	magnetic field
(c)	gravitational field
(d)	both magnetic and gravitational field

30.

The equivalent inductance of two inductors is 2.4 H when connected in parallel and 10 H when connected in series, then the individual inductance is _____

(a)	6H, 4H
(b)	5H, 5H
(c)	7H, 3H
(d)	8H, 2H

Showing 21 to 30 out of 168 Questions