MCQs of Alternating Current

Alternating Current MCQs

MCQs of Alternating Current

Showing 11 to 20 out of 168 Questions

11.

In an A.C. circuit current is 2 A and voltage is 220 V and power is 40 W power factor is _____ .

(a)	0.9
(b)	0.09
(c)	1.8
(d)	0.18

12.

In L-R A.C. circuit at time

t

current is I and time rate of change of current is

\frac{d I}{d t}

what will be the potential difference between the two ends of the inductor ?

(a)	$L \frac{d I}{d t}$
(b)	$\frac{1}{L} \frac{d I}{d t}$
(c)	LI
(d)	$\frac{L}{I}$

13.

V and I are given by the following equation in an A.C. circuit : V = 100 sin(100

t

) V, I = 100 sin

(100 t + \frac{π}{3})

mA. The power in the circuit is equal to _____ W.

(a)	$10^{4}$
(b)	10
(c)	2.5
(d)	5.0

14.

Current of

\frac{50}{π}

Hz frequency is passing through an A.C. circuit having series combination of resistance R = 100

Ω

and inductor L = 1 H, then phase difference between voltage and current is _____ .

(a)	$60 °$
(b)	$45 °$
(c)	$30 °$
(d)	$90 °$

15.

If in an A.C. L-C series circuit

X_{L} > X_{C} .

Hence current _____ .

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

16.

What is the r.m.s value of the current for A.C. current

I = 100 \cos (200 t + 45 °)

(a)	$50 \sqrt{2}$ A
(b)	100 A
(c)	$100 \sqrt{2}$ A
(d)	Zero

17.

Resonance frequency for L-C-R A.C. series circuit is

f_{0} =

_____ .

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

18.

A coil of inductance L and resistance R is connected to an A.C. source of V volt. If the angular frequency of the A.C. source is equal to

ω {rad}^{- 1},

then the current in the circuit will be _____ .

(a)	$\frac{V}{R}$
(b)	$\frac{V}{L}$
(c)	$\frac{V}{R + L}$
(d)	$\frac{V}{\sqrt{R^{2} + ω^{2} L^{2}}}$

19.

One inductor (of inductance L henry) is connected to an A.C. source, then the current flowing through the inductor I = _____ A.

(a)	$\frac{V_{0}}{ωL} \sin (ω t + \frac{π}{2})$
(b)	$\frac{V_{0}}{ωL} \sin (ω t - \frac{π}{2})$
(c)	$V_{0} ωLsin (ω t - \frac{π}{2})$
(d)	$\frac{ωL}{V_{0}} \sin (ω t + \frac{π}{2})$

20.

The potential difference between the two ends of the three components of L-C-R series A.C. circuit are V_L, V_C and V_R respectively. Then voltage of A.C. source is _____ .

(a)	V_L + V_C+ V_R
(b)	V_R + V_L- V_C
(c)	$\sqrt{V_{R}^{2} + (V_{L} + V_{C})^{2}}$
(d)	$\sqrt{V_{R}^{2} + (V_{L} - V_{C})^{2}}$

Showing 11 to 20 out of 168 Questions