MCQs of Alternating Current

Alternating Current MCQs

MCQs of Alternating Current

Showing 121 to 130 out of 168 Questions

121.

In an A.C. circuit, the current lags behind the voltage by

\frac{π}{3}

. The components of the circuit are_____

(a)	R and L
(b)	L and C
(c)	R and C
(d)	only R

122.

In a series L - C - R circuit, the voltage across the resistance, capacitance and inductance is 10 V each. If the capacitor is removed, then the voltage across the inductance will be_____

(a)	10 V
(b)	$10 \sqrt{2} V$
(c)	$\frac{10}{\sqrt{2}} V$
(d)	20 V

123.

An A.C. voltage is given by

V = V_{m}

sin

\frac{2 πt}{T}

. The mean value of voltage calculated over time interval of

\frac{T}{2}

seconds _____

(a)	is always zero
(b)	is never zero
(c)	is always $\frac{2 E_{0}}{π}$
(d)	may be zero

124.

In an A.C. circuit, the potential difference across an inductor and a resistor joined in the series are 16 V and 20 V respectively. The total potential difference across the circuit is _____

(a)	20 V
(b)	25.6 V
(c)	31.9 V
(d)	53.5 V

125.

A mixer of 1500 Ω resistance is connected to an A.C. source of 220 V and 50 cps. So the average value of potential difference across the mixer will be _____

(a)	308 V
(b)	264 V
(c)	220 V
(d)	0

126.

If the instantaneous value of current is I = 20 sin (314 t) A, then the average current for half the cycle will be _____

(a)	10 A
(b)	7.07 A
(c)	6.37 A
(d)	12.74 A

127.

If the instantaneous current in a circuit is given by I = 4 cos

(ω t + ϕ)

A, then r.m.s. value of the current is _____

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

128.

An A.C. circuit resonates at a frequency of 10 kHz. If its frequency is increased to 11 kHz, then _____

(a)	impedance will increase by 1.1 times
(b)	impedance will remain unchanged
(c)	impedance will increase and becomes inductive
(d)	impedance will increase and becomes capacitive

129.

An L - C - R series circuit with 100 Ω resistance is connected to an A.C. source of 200 V and angular frequency 300 radians per second. When only the capacitance is removed, the current lags the voltage by 60⁰. When only the inductance is removed, the current leads the voltage by 60⁰. The current and power dissipated in the L - C - R circuit are respectively _____ and _____

(a)	1 A, 200 watt
(b)	1 A, 400 watt
(c)	2 A, 200 watt
(d)	2 A, 400 watt

130.

The band-width of a series resonant circuit is 500

H_{Z}

and the resonant frequency is 5000

H_{Z}

. The value of R is 100

Ω

, then capacity of condenser will be _____

(a)	$\frac{1}{π} μ F$
(b)	$\frac{1}{2 π} μ F$
(c)	$\frac{1}{5 π} μ F$
(d)	$\frac{1}{10 π} μ F$

Showing 121 to 130 out of 168 Questions