NCERT Class 12 MCQ Quiz Hub

1. Power factor of an ac circuit is a measure of:
virtual power
power lost in the circuit
mean power
All the above

2. The dimensional formula of L/R is similar to that of:
requency
time
length
None of the above

3. Which of the following has dimensions different from the rest?
L/R
1RC
LC−−−√
RC

4. The dimensional formula of impedance is;
[ML2T-2A-2]
ML2T-3A-2]
[ML2T-2A-1]
[ML2T-2A-3]

5. Energy dissipates in LCR circuit in :
L only
C only
R only
All the above

6. An iron core transformer with a turns ratio of 8 : 1 has 120 V applied across the primary. The voltage across the
15 V
120 V
180
960 V

7. What is the ratio of inductive and capacitance reactances in an ac circuit?
1
ω²L
ω²LC
l

8. An acceptor circuit is :
series resonant circuit
parallel resonant circuit
LCR circuit
None of these

9. A broadcast circute broadcasts at 300 m band. A condenser of capacitance 2.4 lµF is available. The value of the inductance required for resonant circuit is:
10-4 H
10-8 H
10-6 H
10-2 H

10. In series resonant circuit:
reactance is zero
current is zero
voltage is zero
None of the above

11. In series resonant circuit:
reactance is zero
current is zero
voltage is zero
None of the above

12. In series resonant circuit:
reactance is zero
current is zero
voltage is zero
None of the above

13. The no. of turns in the primary coil of a transformer is 200 and the no. of turns in the secondary is 10. If 240 V a.c. is applied to primary, the output from the secondary
6 V
12 V
24 V
48 V

14. The no. of turns in the primary coil of a transformer is 200 and the no. of turns in the secondary is 10. If 240 V a.c. is applied to primary, the output from the secondary
6 V
12 V
24 V
48 V

15. The no. of turns in the primary coil of a transformer is 200 and the no. of turns in the secondary is 10. If 240 V a.c. is applied to primary, the output from the secondary
6 V
12 V
24 V
48 V

16. Transformer works on the principle of:
convertor
invertor
mutual induction
self-induction

17. Which of the following effects is not shown in alternating current ?
Chemical effect
Magnetic effect
Heating current
All the above

18. An ac ammeter connected in series in an ac circuit reads 5A. The peak value of current:
5 A (b) (c)
5√2A
5√5 A
Zero

19. The phase difference b/w the A.C. and e.m.f. π2 Which of the following can not be the instituent of the circuit?
LC
L alone
C alone
RL

20. Faraday constant:
depends on the amount of the electrolyte
depends on the current in the electrolyte
is a universal constant
depends on the amount of charge passed through the electrolyte

21. A rejector circuit is:
series resonant circuit
parallel resonant circuit
LCR circuit
None of the above

22. In pure inductive circuit current
lags behind emf by π/2
leads the emf by π/2
lags behind emf by π
leads the emf by π

23. The current through an inductor of 1H is given by I = 3t sin t. The voltage across the inductor of 1 H is:
3 sin t + 3 cos t
3 sin t + 3t cos t
3 cos t + t sin t
3t cos t + sin t

24. Two coils X and Y are connected in series across a 240 V, 50 Hz supply. The resistance of X is 5Ω and inductance of Y is 0.02 H. The power consumed is 3 kW and the power factor is 0.75. The impedance of the circuit is:
0.144 Ω
1.44
14.4 Ω
144 Ω

25. In the above problem, the value of the resistance of the coil Y is:
0.58 Ω
5.8 Ω
1.16
11.6 Ω

26. An electric circuit containing capacitor only suffers:
equal resistance for A.C. and D.C. (b)
Resistance of A.C. > Resistance of D.C.
Resistance for A.C. < Resistance of D.C.
offers infinite resistance for D.C.

27. The average power dissipation in pure inductance or capacitance is: (a) 12 LI²
12 LI²
3/2 CV²
either (a) or (b)
zero