JEE Main - Capacitance, capacitors and energy stored Online Test (MCQ Quiz)

1. What is the unit of capacitance in the SI system?

A) Volt B) Ampere C) Farad D) Ohm

2. A capacitor is a device used to store:

A) Magnetic energy B) Electrical energy C) Mechanical energy D) Thermal energy

3. The capacitance of a parallel plate capacitor is given by C = ε₀A/d, where A is the area of the plates and d is the distance between them. If the distance between the plates is doubled, the capacitance will:

A) Double B) Halve C) Remain the same D) Become four times

4. If the area of the plates of a parallel plate capacitor is doubled, its capacitance will:

A) Double B) Halve C) Remain the same D) Become four times

5. What happens to the capacitance of a parallel plate capacitor if a dielectric material is introduced between the plates?

A) It decreases B) It increases C) It remains unchanged D) It becomes zero

6. The dielectric constant of a material is always:

A) Less than 1 B) Equal to 1 C) Greater than or equal to 1 D) Zero

7. If a capacitor has a capacitance of 1 Farad and is charged to a potential difference of 1 Volt, how much charge does it store?

A) 1 Coulomb B) 1 Ampere C) 1 Joule D) 1 Watt

8. The energy stored in a capacitor is given by the formula:

A) U = CV B) U = Q/C C) U = 1/2 CV² D) U = Q²/V

9. If the voltage across a capacitor is doubled, the energy stored in it will:

A) Double B) Halve C) Remain the same D) Become four times

10. Two capacitors C1 and C2 are connected in series. The equivalent capacitance Ceq is given by:

A) Ceq = C1 + C2 B) 1/Ceq = 1/C1 + 1/C2 C) Ceq = C1C2 / (C1 + C2) D) Ceq = C1 / C2

11. When capacitors are connected in parallel, the total capacitance is:

A) The sum of individual capacitances B) The reciprocal of the sum of reciprocals of individual capacitances C) The product of individual capacitances D) The average of individual capacitances

12. A capacitor of 10 µF is charged to 100 V. The energy stored in the capacitor is:

A) 0.1 J B) 0.05 J C) 0.5 J D) 1 J

13. Which of the following is NOT a type of capacitor?

A) Ceramic capacitor B) Electrolytic capacitor C) Inductor capacitor D) Variable capacitor

14. The capacitance of a spherical capacitor of radius R is proportional to:

A) R B) 1/R C) R² D) √R

15. What is the unit of charge?

A) Farad B) Volt C) Ampere D) Coulomb

16. Dielectric strength is the maximum electric field a dielectric material can withstand without:

A) Losing its charge B) Becoming a conductor C) Changing its capacitance D) Dissipating energy

17. If a capacitor is charged by a battery and then disconnected, and the plates are moved farther apart, the potential difference across the capacitor will:

A) Increase B) Decrease C) Remain the same D) Become zero

18. If a capacitor is charged by a battery and remains connected, and the plates are moved farther apart, the charge on the capacitor will:

A) Increase B) Decrease C) Remain the same D) Become zero

19. The energy density in the electric field between the plates of a parallel plate capacitor is given by:

A) 1/2 ε₀E B) 1/2 ε₀E² C) ε₀E D) ε₀E²

20. A capacitor is essentially a device to increase the electrical energy storage capacity of a circuit by:

A) Increasing resistance B) Decreasing inductance C) Increasing capacitance D) Decreasing voltage

21. What is the effect of increasing the thickness of the dielectric between the plates of a parallel plate capacitor, assuming the dielectric constant remains the same?

A) Capacitance increases B) Capacitance decreases C) Capacitance remains unchanged D) Capacitance becomes zero

22. Two capacitors, 2µF and 4µF, are connected in series. What is the equivalent capacitance?

A) 6µF B) 2µF C) 4/3 µF D) 3/2 µF

23. Two capacitors, 2µF and 4µF, are connected in parallel. What is the equivalent capacitance?

A) 6µF B) 2µF C) 4/3 µF D) 3/2 µF

24. What is the maximum energy that can be stored in a 100 µF capacitor rated for 10 V?

A) 10 J B) 5 J C) 5 mJ D) 10 mJ

25. When a dielectric is inserted into a charged capacitor disconnected from the battery, the electric field between the plates:

A) Increases B) Decreases C) Remains the same D) Becomes zero

26. The capacitance of a capacitor is defined as the ratio of the charge on one of its conductors to the:

A) Area of the plates B) Distance between the plates C) Potential difference between the plates D) Dielectric constant of the material

27. Which type of capacitor is suitable for high-frequency applications and has a stable capacitance value?

A) Electrolytic capacitor B) Tantalum capacitor C) Ceramic capacitor D) Variable capacitor

28. A capacitor with capacitance C is charged to a voltage V. If the voltage is increased to 2V, the stored energy becomes:

A) C B) 2C C) 4 times the original energy D) 2 times the original energy

29. In a parallel plate capacitor, if the permittivity of the dielectric material is ε, the capacitance is given by C = εA/d. If a vacuum is replaced by a material with dielectric constant k, the capacitance becomes:

A) C/k B) Ck C) C D) k/C

30. The unit of energy stored in a capacitor is:

A) Farad B) Coulomb C) Joule D) Volt

31. If a capacitor is charged and then discharged, the energy stored is dissipated as:

A) Heat B) Light C) Sound D) Magnetic field

32. What is the capacitance of a capacitor with a charge of 6 µC and a potential difference of 3 V?

A) 1 µF B) 2 µF C) 3 µF D) 18 µF

33. The capacitance of a parallel plate capacitor filled with a dielectric material is 10 µF. If the dielectric is removed, the capacitance will:

A) Increase B) Decrease C) Remain the same D) Become zero

34. A variable capacitor is used in tuning circuits because its capacitance can be:

A) Continuously changed B) Fixed at a high value C) Fixed at a low value D) Rapidly discharged

35. What is the potential difference across a 5 µF capacitor storing 10 mJ of energy?

A) 1 V B) 2 V C) 20 V D) 200 V

36. The maximum charge a capacitor can hold without breakdown is determined by its:

A) Capacitance B) Voltage rating C) Dielectric strength D) Plate area

37. Electrolytic capacitors are polarized and must be connected with the correct polarity. This is because:

A) They have very low capacitance B) Their dielectric layer is very thin and can be damaged by reverse voltage C) They are designed for AC circuits D) They store energy magnetically

38. If two capacitors C1 and C2 are connected in series and charged by a voltage V, the voltage across C1 is given by:

A) V * C2 / (C1 + C2) B) V * C1 / (C1 + C2) C) V * C2 / (C1 - C2) D) V * C1 / (C2 - C1)

39. If two capacitors C1 and C2 are connected in parallel and charged by a voltage V, the charge on C1 is given by:

A) V / C1 B) V * C1 C) V / (C1 + C2) D) V * (C1 + C2)

40. What is the capacitance of a capacitor if it stores 0.001 C of charge when the potential difference across it is 100 V?

A) 10 µF B) 100 µF C) 1 mF D) 10 mF

41. When a dielectric material is inserted between the plates of a charged capacitor (disconnected from the source), the capacitance:

A) Increases B) Decreases C) Remains the same D) Becomes infinite

42. The ability of a dielectric material to reduce the electric field between the plates of a capacitor is measured by its:

A) Dielectric strength B) Dielectric constant C) Permittivity D) Conductivity

43. A capacitor of 1 µF is charged to 10 V. If the voltage is increased to 20 V, the energy stored increases by a factor of:

A) 2 B) 4 C) 8 D) 16

44. What is the unit of dielectric constant?

A) Farad B) Coulomb/Volt C) Dimensionless D) Volt/Meter

45. Which of the following statements is true for capacitors in parallel?

A) Charge is divided among capacitors B) Voltage across each capacitor is the same C) Total capacitance is the reciprocal of the sum of reciprocals D) Energy stored is the sum of energies stored in each capacitor

46. Which of the following statements is true for capacitors in series?

A) Charge is the same on each capacitor B) Voltage is divided among capacitors C) Total capacitance is the sum of individual capacitances D) Energy stored is the sum of energies stored in each capacitor

47. A 1 µF capacitor is charged to 100 V. The charge stored on the capacitor is:

A) 100 µC B) 10 µC C) 1 mC D) 0.1 mC

48. The energy stored in a capacitor can also be expressed as:

A) U = QV B) U = Q²/C C) U = CV²/2 D) U = Q/C

49. If the distance between the plates of a parallel plate capacitor is halved, while keeping the charge constant, the potential difference between the plates will:

A) Double B) Halve C) Remain the same D) Become four times

50. What is the work done to move a charge q from infinity to a point where the potential is V?

A) q/V B) V/q C) qV D) -qV

Capacitance, capacitors and energy stored - Online Test

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