MCQs of Alternating Current

Alternating Current MCQs

MCQs of Alternating Current

Showing 101 to 110 out of 168 Questions

101.

What is the power factor of an A.C. circuit having resistance (R) and inductance (L) connected in series when an angular velocity is ω ?

(a)	$\frac{R}{ωL}$
(b)	$\frac{R}{(R^{2} + ω^{2} L^{2})^{\frac{1}{2}}}$
(c)	$\frac{ωL}{R}$
(d)	$\frac{R}{(R^{2} - ω^{2} L^{2})^{\frac{1}{2}}}$

102.

In a L-C-R circuit capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to _____

(a)	4L
(b)	2L
(c)	$\frac{L}{2}$
(d)	$\frac{L}{4}$

103.

A.C. current reduces to zero, 120 times in 1 s. So frequency of the A.C is _____ Hz.

(a)	50
(b)	100
(c)	60
(d)	120

104.

If angular frequency of an A.C. souurce used in an L-C-R circuit is decreased, then capacitive reactance _____ and inductive reactance _____

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

105.

An A.C. circuit contains 12 Ω resistance and a capacitive reactance of capacitor 9 Ω in series. So value of impedance of the circuit is _____

(a)	15 Ω
(b)	21 Ω
(c)	3 Ω
(d)	$3 \sqrt{7}$ Ω

106.

The unit of

\frac{1}{ωL}

and ωC respectively _____

(a)	$℧, ℧$
(b)	$℧, Ω$
(c)	$Ω, ℧$
(d)	$Ω, Ω$

107.

Which quantity enables us to know sharpness of resonance ?

(a)	$\frac{1}{R} \sqrt{LC}$
(b)	$\frac{1}{R} \sqrt{\frac{C}{L}}$
(c)	$R \sqrt{\frac{L}{C}}$
(d)	$\frac{ω_{0}}{Δ ω}$

108.

The relation between output power and input power for an ideal transformer is _____

(a)	P_i = P_o
(b)	P_i > P_o
(c)	P_i < P_o
(d)	none of these

109.

What is meant by transformation ratio ?

(a)	$r = N_{1} N_{2}$
(b)	$r = \frac{N_{1}}{N_{2}}$
(c)	$r = \frac{1}{N_{1} N_{2}}$
(d)	$r = \frac{N_{2}}{N_{1}}$

110.

Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication ?

(a)	R = 15 Ω, L = 3.5 H, C= 30 μF
(b)	R = 25 Ω, L = 1.5 H, C= 45 μF
(c)	R = 20 Ω, L = 1.5 H, C= 35 μF
(d)	R = 25 Ω, L = 2.5 H, C= 45 μF

Showing 101 to 110 out of 168 Questions