Alternating Current Class 12 MCQs Questions with Answers

1. In an L.C.R. series a.c. circuit, the current

2. Power factor is one for

3. For minimum dissipation of energy in the circuit the power factor should be

4. A capacitor has capacitance C and reactance X, if capacitance and frequency become double, then reactance will be

5. Quantity that remains unchanged in a transformer is

6. Transformer works on the principle of:

7. A bulb connected in series with a solenoid is lit by an AC source. If a soft iron core is introduced in the solenoid then,

8.  
A rejector circuit is:

9. In which of the following circuits the maximum power dissipation is observed?

10. Consider the following statements and then select the correct statements.
I. Most of the electrical device we use require AC voltage.
II. Most of the electrical energy sold by power companies is transmitted and distributed as alternating current.
III. AC voltage can be easily and efficiently converted from one to the other by means of transformers.

11.  
In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?

12. Which of the following effects is not shown in alternating current ?

13. The transformation ratio in the step-up transformer is

14.  
Identify the principle behind the working of an a.c. generator.

15. In parallel resonant circuit:

16. Power factor of an ac circuit is a measure of:

17. The dimensional formula of impedance is;

18. A rejector circuit is:

19. An AC voltage source of variable angular frequency ω and fixed amplitude V0 is connected in series with a capacitance C and an electric bulb of resistance R (inductance zero). When ω is increased then,

20. Alternating current can not be measured by D.C. ammeter, because