Capacitor MCQ | Capacitance MCQ

1. An isolated sphere of radius 1 cm is kept in air. Its capacitance will be

  1. 1.11 pF
  2. 2.2 pF
  3. 2.1 pF
  4. 1.8 pF
Answer
Answer. a

2. The reactance of capacitors increases as

  1. applied voltage increases
  2. AC frequency increases
  3. applied voltage decreases
  4. AC frequency decreases
Answer
Answer. d

3. Which of the following materials has the maximum dielectric strength?

  1. Porcelain
  2. Glass
  3. Polystyrene
  4. Soft rubber
Answer
Answer. d

4. The current through a capacitor is given by

  1. $i=C\frac{dv}{dt}$
  2. $i=\frac{1}{C}\frac{dv}{dt}$
  3. $i=C\frac{d^2v}{dt^2}$
  4. $i=\frac{1}{C}\frac{d^2v}{dt^2}$
Answer
Answer. a

5. When the plate area of a parallel plate capacitor is increased, keeping the capacitor voltage constant, the force between the plates

  1. increases
  2. decreases
  3. remains constant
  4. becomes zero
Answer
Answer. a

6. When the total charge in a capacitor is doubled, the energy stored

  1. remains the same
  2. is halved
  3. is doubled
  4. is quadrupled
Answer
Answer. d

7. Potential applied across a 2 F capacitor is 10 V. Energy stored in it will be

  1. 200 J
  2. 100 J
  3. 20 J
  4. 10 J
Answer
Answer. b

8. If distance between two plates of a parallel plate capacitor is halved, the capacitance

  1. doubles
  2. quadruples
  3. is halved
  4. remains the same
Answer
Answer. a

9. A 1 μF capacitor is connected to 12 V battery. The energy stored in the capacitor is

  1. 12 x 10-6 J
  2. 24 x 10-6 J
  3. 48 x 10-6 J
  4. 72 x 10-6 J
Answer
Answer. d

10. If three 15 μF capacitors are connected in series, the net capacitance is

  1. 5 μF
  2. 40 μF
  3. 50 μF
  4. 30 μF
Answer
Answer. a

11. Two capacitor C1 and C2 have C1 = 20 μF and C2 = 30 μF, are connected in parallel across a 100V source. The net capacitance of the circuit is?

  1. 10 μF
  2. 50 μF
  3. 60 μF
  4. 12 μF
Answer
Answer. b

12. The capacitance of a capacitor is not affected by

  1. Plate area
  2. Plate separation
  3. Nature of dielectric
  4. Plate thickness
Answer
Answer. d

13. Which of the following capacitors are used in D.C. circuits?

  1. Mica
  2. Air
  3. Ceramic
  4. Electrolytic
Answer
Answer. d

14. A bank of condensor across the load of the factor is used for

  1. improving the power factor
  2. decreasing the power factor
  3. progress in the fluctuations
  4. quick start of the motors
Answer
Answer. a

15. When two capacitors are connected in series, their total value of capacitance

  1. Remains same
  2. Reduces
  3. Increases
  4. None of these
Answer
Answer. b

16. Three capacitors of 10 μF, 20 μF and 40 μF are connected in parallel across 100 V. The total charge stored in capacitors is

  1. 5.9 x 10-3 C
  2. 4 x 10-3 C
  3. 7 x 10-3 C
  4. 14 x 10-3 C
Answer
Answer. c

17. An isolated sphere has a capacitance of 50 pf. If its potential is raised to 104 volts, radius and charge will be respectively,

  1. 54 cm, 0.5 μC
  2. 4.5 cm, 5.0 μC
  3. 45 cm, 0.5 μC
  4. 45 cm, 0.5 μC
Answer
Answer. c

18. If four 10 μF capacitors are connected in parallel, the net capacitance is

  1. 2.5 μF
  2. 40 μF
  3. 15 μF
  4. 20 μF
Answer
Answer. b

19. A 20 micro farad capacitor is connected across an ideal voltage source. The current in the capacitor

  1. will be very high at first, then exponentially decay and at steady state will become zero.
  2. will be zero at first, then exponentially rise
  3. will be very high at first, then exponentially decay
  4. None of these are true
Answer
Answer. a

20. A 10 μF and a 20 μF capacitor are in series. The combination is supplied at 150 V from a sinusoidal voltage source. The voltage across the 20 μF capacitor is then

  1. 75 V
  2. 125 V
  3. 100 V
  4. 50 V
Answer
Answer. d

21. Three 3 μF capacitors are in series. A 6 μF in parallel with this series arrangement. The equivalent capacitance of this combination is

  1. 15 μF
  2. 7 μF
  3. 1 μF
  4. 3.6 μF
Answer
Answer. b

22. Two lossy capacitors with equal capacitance values and power factors of 0.01 and 0.02 are in parallel, and the combination is supplied from a sinusoidal voltage source. The power factor of the combination is

  1. 0.015
  2. 0.03
  3. 0.0002
  4. 0.01
Answer
Answer. a

23. If a 10 μF capacitor is connected to a voltage source with v(t) = 50 sin 2000t V, then the current through the capacitor is ___________ A.

  1. cos 2000t
  2. 500 cos 2000t
  3. 106 cos 2000t
  4. 5 x 10-4 cos 2000t
Answer
Answer. a

24. A piece of oil-soaked paper has been inserted between the plates of a parallel plate capacitor. Then the potential difference between the plates will

  1. increase
  2. decrease
  3. remain unaltered
  4. become zero
Answer
Answer. b

25. The reactance of 1 farad capacitance when connected to a DC circuit is

  1. 1 Ω
  2. infinite
  3. zero ohms
  4. 0.5 Ω
Answer
Answer. b

26. The total capacitance of two 40 μF series-connected capacitors in parallel with a 4 μF capacitor is

  1. 3.8 μF
  2. 5 μF
  3. 24 μF
  4. 44 μF
Answer
Answer. c

27. A circuit requires a capacitor of 100 μF, 25 V. The capacitor can be

  1. Paper capacitor
  2. Electrolytic capacitor
  3. Ceramic capacitor
  4. Any type of capacitor
Answer
Answer. b

28. A capacitor stores energy in

  1. An electric field
  2. An electromagnetic field
  3. A magnetic field
  4. Dielectric dipole
Answer
Answer. a

29. Farad is the unit of?

  1. Inductance
  2. Voltage
  3. Current
  4. Capacitance
Answer
Answer. d

30. Two capacitors of 2 F each are connected in series to a 1V battery. The total charge supplied by the battery to capacitors is

  1. 1 C
  2. 2 C
  3. 0.5 C
  4. 0.25 C
Answer
Answer. a
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