Alternating Current  MCQs

MCQs of Alternating Current

Showing 1 to 10 out of 168 Questions
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1.
In an A.C. circuit in 1 second current reduces to zero value 120 times. Hence the frequency of A.C. current is _____ Hz.
(a) 50
(b) 100
(c) 60
(d) 120
Answer:

Option (c)

2.
On decreasing the angular frequency of A.C. source used in L-C-R series circuit, the capacitive reactance _____ and inductive reactance _____ .
(a) Increases, Decreases
(b) Increases, Increases
(c) Decreases, Increases
(d) Decreases, Decreases
Answer:

Option (a)

3.
When does the impedance of a series L-C-R AC circuit become minimum ?
(a) When the resistance is equal to zero.
(b) When the impedance is equal to zero.
(c) When the electric current is equal to zero.
(d) When the imaginary part of the impedance is equal to zero.
Answer:

Option (d)

4.
The Value of the Q factor in an L-C-R series circuit is _________ .
(a) dependent on the frequency of the A.C. source.
(b) dependent on the values of all the three components L, R and C.
(c) dependent only on the values of L and C.
(d) it may or may not depend on the power factor.
Answer:

Option (b)

5.
In R-C circuit when charge on the plates of the capacitor is increasing, the energy obtained from the source is stored in _____ .
(a) electric field
(b) magnetic field
(c) gravitational field
(d) both magnetic field and gravitational field
Answer:

Option (a)

6.
The output power in a step-up transformer is _____ .
(a) greater than the input power
(b) equal to the input power
(c) maintained even during the power cut
(d) less than the input power
Answer:

Option (d)

7.
In an L-C oscillator circuit having a completely charged capacitor, with the passage of time _____ .
(a) The electric current increases gradually.
(b) The energy of the circuit continuously increases.
(c) The energy of the circuit continuously decreases.
(d) There is a continuous absorption of the electromagnetic wave.
Answer:

Option (c)

8.
The equivalent inductance of two inductors is 2.4 H when connected in paralled and 10 H when connected in series, then the individual inductance is
(a) 6 H, 4 H
(b) 5 H, 5 H
(c) 7 H, 3 H
(d) 8 H, 2 H
Answer:

Option (a)

9.
Which device is used to increase or decrease A.C. voltage ?
(a) Oscillator
(b) Voltmeter
(c) Transformer
(d) Rectifier
Answer:

Option (c)

10.
For step-down transformer value of transformation ratio is _________ .
(a) r > 1
(b)  r < 1
(c)  r = 1
(d)  r = 0
Answer:

Option (b)

Showing 1 to 10 out of 168 Questions
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