Alternating Current  MCQs

MCQs of Alternating Current

Showing 111 to 120 out of 168 Questions
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111.
The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. the power factor of this circuit is
(a) 0.8
(b) 1.0
(c) 0.4
(d) 0.5
Answer:

Option (a)

112.
A 100 Ω resistance and a capacitor of 100 Ω reactance are connected in series across a 220 V source. When the capacitor is 50% charged, the peak value of the displacement current is
(a) 4.4 A
(b) 112 A
(c) 2.2 A
(d) 11A
Answer:

Option (c)

113.
In an L-C-R series circuit, if R = 10 Ω, XL = 8 Ω and XC = 6 Ω, then the total impedance of the circuit is _____.
(a) 10.2 Ω
(b) 17.2 Ω
(c) 10 Ω
(d) None of the above
Answer:

Option (a)

114.
In an L-C-R series circuit, if R = 10 Ω, XL = 8 Ω and XC = 6 Ω, then the phase difference between voltage and current is _____ .
(a) 0.2º
(b) 11.3º
(c) 30º
(d) 45º
Answer:

Option (b)

115.
The electric mains in a house are marked 120 V, 50 Hz. The equation of instantaneous voltage is _____ V.
(a) 120 sin 50πt
(b) 120 2 sin 50πt
(c) 120 sin 100πt
(d) 120 2 sin 100πt
Answer:

Option (d)

116.
In an A.C. circuit, the equation of emf is as follows : V = 5 cos (100 t). The amplitude of the current in an L-R circuit of inductance 0.03 H and resistance 4 Ω is _____ .
(a) 42 A
(b) 47 A
(c) 1 A
(d) 0.8 A
Answer:

Option (c)

117.
An air core coil and electric bulb are connected in series with an A.C. source. If an iron rod is put in the coil, then the intensity of the bulb will _____ .
(a) be same
(b) increase
(c) decrease
(d) decrease or increase
Answer:

Option (c)

118.
A capacitor of capacitance 2  μF is connected in a tank circuit of an oscillator oscillating with a frequency of 1 Hz. If the current flowing in the circuit is 2 mA, then the voltage across the capacitor will be _____ .
(a) 0.16 V
(b) 0.32 V
(c) 80 V
(d) 160 V
Answer:

Option (d)

119.
A 240 V, 50 Hz A.C. source is connected to a circuit with an inductance of 0.2 H and a resistance of 20 Ω in series. The current in the circuit is _____
(a) 0.33 A
(b) 3.3 A
(c) 13.3 A
(d) 3.64 A
Answer:

Option (d)

120.
The inductance of a coil is 0.70 H. An A.C. source of 120 V is connected in series with it. If the frequency of A.C. is 60 Hz, then the current which is flowing in the inductance, will be _____
(a) 4.55 A
(b) 0.35 A
(c) 0.45 A
(d) 3.55 A
Answer:

Option (c)

Showing 111 to 120 out of 168 Questions
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