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

- 1.11 pF
- 2.2 pF
- 2.1 pF
- 1.8 pF

2. The reactance of capacitors increases as

- applied voltage increases
- AC frequency increases
- applied voltage decreases
- AC frequency decreases

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

- Porcelain
- Glass
- Polystyrene
- Soft rubber

4. The current through a capacitor is given by

- $i=C\frac{dv}{dt}$
- $i=\frac{1}{C}\frac{dv}{dt}$
- $i=C\frac{d^2v}{dt^2}$
- $i=\frac{1}{C}\frac{d^2v}{dt^2}$

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

- increases
- decreases
- remains constant
- becomes zero

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

- remains the same
- is halved
- is doubled
- is quadrupled

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

- 200 J
- 100 J
- 20 J
- 10 J

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

- doubles
- quadruples
- is halved
- remains the same

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

- 12 x 10
^{-6}J - 24 x 10
^{-6}J - 48 x 10
^{-6}J - 72 x 10
^{-6}J

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

- 5 μF
- 40 μF
- 50 μF
- 30 μF

11. Two capacitor C_{1} and C_{2} have C_{1} = 20 μF and C_{2} = 30 μF, are connected in parallel across a 100V source. The net capacitance of the circuit is?

- 10 μF
- 50 μF
- 60 μF
- 12 μF

12. The capacitance of a capacitor is not affected by

- Plate area
- Plate separation
- Nature of dielectric
- Plate thickness

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

- Mica
- Air
- Ceramic
- Electrolytic

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

- improving the power factor
- decreasing the power factor
- progress in the fluctuations
- quick start of the motors

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

- Remains same
- Reduces
- Increases
- None of these

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

- 5.9 x 10
^{-3}C - 4 x 10
^{-3}C - 7 x 10
^{-3}C - 14 x 10
^{-3}C

17. An isolated sphere has a capacitance of 50 pf. If its potential is raised to 10^{4} volts, radius and charge will be respectively,

- 54 cm, 0.5 μC
- 4.5 cm, 5.0 μC
- 45 cm, 0.5 μC
- 45 cm, 0.5 μC

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

- 2.5 μF
- 40 μF
- 15 μF
- 20 μF

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

- will be very high at first, then exponentially decay and at steady state will become zero.
- will be zero at first, then exponentially rise
- will be very high at first, then exponentially decay
- None of these are true

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

- 75 V
- 125 V
- 100 V
- 50 V

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

- 15 μF
- 7 μF
- 1 μF
- 3.6 μF

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

- 0.015
- 0.03
- 0.0002
- 0.01

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.

- cos 2000t
- 500 cos 2000t
- 10
^{6}cos 2000t - 5 x 10
^{-4}cos 2000t

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

- increase
- decrease
- remain unaltered
- become zero

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

- 1 Ω
- infinite
- zero ohms
- 0.5 Ω

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

- 3.8 μF
- 5 μF
- 24 μF
- 44 μF

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

- Paper capacitor
- Electrolytic capacitor
- Ceramic capacitor
- Any type of capacitor

28. A capacitor stores energy in

- An electric field
- An electromagnetic field
- A magnetic field
- Dielectric dipole

29. Farad is the unit of?

- Inductance
- Voltage
- Current
- Capacitance

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 C
- 2 C
- 0.5 C
- 0.25 C