Capacitance and Dielectrics — 50 MCQs

1. A capacitor is a device used to store:

2. The SI unit of capacitance is:

3. Capacitance is defined as:

4. One farad is equal to:

5. On a Q–V graph for a capacitor, the gradient of the straight line represents:

6. Practical capacitor values are most commonly expressed in:

7. Which of the following is NOT a typical use of a capacitor?

8. The two plates of a charged capacitor carry:

9. A capacitor blocks:

10. If the potential difference across a capacitor is doubled, the charge stored (assuming constant C):

11. The capacitance of a capacitor depends on:

12. A dielectric material is best described as:

13. If ΔQ = 4 μC produces ΔV = 2 V across a capacitor, its capacitance is:

14. A capacitor with a steeper Q–V graph compared to another indicates:

15. Which symbol correctly represents permittivity of free space?

16. The formula for the capacitance of a parallel plate capacitor with vacuum between the plates is:

17. In the derivation of C = ε₀A/d, which law is applied to find the electric field between the plates?

18. If the plate area of a parallel plate capacitor is doubled while separation remains constant, the capacitance:

19. If the plate separation of a parallel plate capacitor is halved while area remains constant, the capacitance:

20. The electric field between the plates of a charged parallel plate capacitor (vacuum) is given by:

21. Outside the plates of an ideal parallel plate capacitor, the net electric field is:

22. A parallel plate capacitor has plates of area 0.01 m² separated by 2 mm in vacuum. Its capacitance is approximately: (ε₀ = 8.85 × 10⁻¹² F/m)

23. Which graph correctly represents C plotted against 1/d for a parallel plate capacitor (A constant)?

24. Doubling both the plate area and the plate separation of a parallel plate capacitor leaves the capacitance:

25. If a parallel plate capacitor's area is tripled and its separation is also tripled, the new capacitance compared to the original is:

26. For capacitors connected in series, which quantity is the same across each capacitor?

27. For capacitors connected in parallel, which quantity is the same across each capacitor?

28. The equivalent capacitance of capacitors in series is:

29. The equivalent capacitance of capacitors in parallel is:

30. Two capacitors of 4 μF and 4 μF are connected in series. The equivalent capacitance is:

31. Two capacitors of 4 μF and 4 μF are connected in parallel. The equivalent capacitance is:

32. Three identical capacitors of capacitance C are connected in series. The equivalent capacitance is:

33. Two capacitors, 2 μF and 3 μF, are connected in series across a 10 V battery. The charge on each capacitor is:

34. Two capacitors, 2 μF and 3 μF, connected in parallel across a 10 V battery. The total charge supplied is:

35. A 6 μF capacitor is in series with a parallel combination of 3 μF and 3 μF. The total equivalent capacitance is:

36. Four identical capacitors of 8 μF are connected: two in series, and this series pair is connected in parallel with the other two capacitors also in series. The total capacitance is:

37. In a series combination of unequal capacitors, the capacitor with the smallest capacitance:

38. In a parallel combination of unequal capacitors, the capacitor with the largest capacitance:

39. The energy stored in a charged capacitor is given by the area under which graph?

40. The correct expression for energy stored in a capacitor is:

41. Why is E = QV (without the factor ½) incorrect for a capacitor?

42. A 5 μF capacitor is charged to 100 V. The energy stored is:

43. If the potential difference across a capacitor is doubled, the energy stored:

44. A capacitor stores charge 8 μC at 4 V. The energy stored is:

45. Two capacitors of equal capacitance C are first connected in series and then in parallel across the same voltage V. The ratio of energy stored (series : parallel) is:

46. When a dielectric is placed in an external electric field, its molecules become:

47. When a dielectric slab completely fills the gap of a parallel plate capacitor, the capacitance becomes:

48. An isolated, charged parallel plate capacitor (disconnected from the battery) has a dielectric inserted between its plates. Which of the following remains constant?

49. A parallel plate capacitor remains connected to a battery while a dielectric is inserted. Which quantity stays constant?

50. The bound (induced) charge that appears on the surface of a dielectric in an external field arises because: