Welcome to your Chapter 7 Alternating Current MCQs

1.
A 100 turn coil of area 0.1 m2 rotates at half a revolution per second. It is placed in a uniform magnetic field of 0.01 T perpendicular to the axis of rotation of the coil. Calculate the maximum voltage generated in the coil?

2.
An a.c. generator consists of a coil of 1000 turns and cross-sectional area of 3m2, rotating at a constant angular speed of 60 rad s-1 in a uniform magnetic field 0.04 T. The resistance of the coil is 500Ω. Calculate the maximum current drawn from the generator.

3.
‘X’ is a rectangular coil consisting of a large number of turns of copper wire wound over a soft iron core in an a.c. generator. Identify X.

4.
Determine the rms value of current in the circuit if a 50 Ω resistor is connected across an ac source of 200 V, 50 Hz?

5.
Calculate the rms voltage, if the peak value of an a.c. supply is 300 V.

6.
Find out the net power consumed over a full cycle, if a 150 Ω resistor is connected to a 350 V, 100 Hz ac supply.

7.
Which value of the current do you measure with an a.c. ammeter?

8.
What does a phasor represent?

9.
Find the true statement.

10.
In which type of circuit the value of power factor will be minimum?

11.
At what frequency will a coil, which has an inductance of 2.5 H, have a reactance of 3500 Ω?

12.
Determine the peak current if an inductor of inductance 500 mH is connected to an ac source of peak emf 650 V and frequency 100 Hz

13.
How will the capacitive reactance be affected if the frequency is doubled?

14.
Give the SI unit of capacitive reactance.

15.
A 1.50 μF capacitor is connected to a 220 V, 50 Hz source. If the frequency is doubled, what happens to the capacitive reactance?

16.
Which of the following is usually taken to make the core of a transformer?

17.
In a step-down transformer, the number of turns in the secondary coil is 20 and the number of turns in the primary coil is 100. If the voltage applied to the primary coil is 120 V, then what is the voltage output from the secondary coil?

18.
Find the true statement.

19.
What is the power factor in a pure resistive circuit?

20.
Which among the following varies in both magnitude and sign over a cycle?