Electrostatic Potential and Capacitance Mock Test – Class 12 Physics

1. After a charged parallel-plate capacitor is disconnected from the battery, a dielectric of constant is fully inserted. The charge on the plates remains:

2. Consider the statements about reference level in electrostatic potential.
I. Potential value at a point is always stated relative to some chosen zero level.
II. For isolated charge distributions, infinity is commonly chosen as .
III. Changing the reference level changes all electric field directions automatically.

3. For a capacitor charged to a fixed voltage , the force of attraction between plates can be found from and . If the plate separation is reduced while is kept fixed, the magnitude of the attractive force:

4. The electric field just outside a charged conductor is related to surface charge density by:

5. Assertion: The torque on a dipole in a uniform electric field is maximum at .
Reason: At , the potential energy of the dipole is minimum.

6. At any point on an equipotential surface, the electric field is directed:

7. The row that correctly compares dielectric insertion in two conditions is:

8. Three statements about conductors in electrostatic equilibrium are given.
I. The electric field inside the conducting material is zero.
II. The conductor is an equipotential body.
III. A non-zero tangential electric field can persist on the surface.

9. Two capacitors and are connected in series across a battery. The charge on each capacitor and the voltage across the capacitor are:

10. A mixed electrostatic calculation is described below.

The external work required is:

11. A dipole initially at is allowed to rotate freely in a uniform electric field. Ignoring energy losses, it tends first to rotate toward:

12. A network has and capacitors connected in parallel, and this parallel group is connected in series with a capacitor. The equivalent capacitance is:

13. A capacitor is charged by a source from to final charge . The -versus- graph is a straight line through the origin. If the final values are and , the stored energy is:

14. Three statements about equipotential surfaces are listed.
I. is perpendicular to an equipotential surface.
II. Closer equipotential surfaces indicate a stronger electric field for the same potential difference.
III. A charge moving along an equipotential surface always has maximum change in potential energy.

15. With a parallel-plate capacitor connected to a battery, the potential difference remains constant. If the plate separation is reduced to half, the charge on the plates:

16. A point charge is at the centre of a spherical equipotential surface of radius . If a small positive test charge moves along the surface, the work done by the electrostatic field is:

17. In the previous charge-sharing type of situation, why is electrostatic energy not conserved in the final capacitor energies?

18. A graph is plotted between capacitance and plate area for a parallel-plate capacitor with fixed separation and fixed medium. The graph should be:

19. In a basic circuit idea, a capacitor is mainly introduced as a device that:

20. The SI unit of capacitance follows from . It is:

21. Read the situation below and answer the question.

What field does the test charge experience inside the cavity?

22. A record shows that of external work is needed to bring a small positive test charge of from the reference point to a point . The electrostatic potential at is:

23. The graph description below refers to a negative point charge.

The slope of this graph is:

24. A capacitor is charged to and then disconnected. It is then connected in parallel to an identical uncharged capacitor. The final common potential difference is:

25. An isolated spherical conductor has capacitance . If its potential is raised to , the charge on it is:

26. A charge of is moved between two points, and the work associated with the movement is . The potential difference calculated from work per unit charge is:

27. A square has charges and at one pair of opposite corners, while the other two opposite corners are empty. At the centre of the square:

28. A capacitor is charged from a battery of voltage through ordinary connecting wires. The energy supplied by the battery and the energy finally stored in the capacitor are:

29. For , where is in and is in , the electric field component is:

30. The electrostatic potential energy of two point charges and separated by distance , taking at infinity, is:

31. A neutral hollow conductor contains a charge inside its cavity. The charges induced on the inner and outer surfaces of the conductor are:

32. Three statements about a Van de Graaff generator are given.
I. Charge delivered to the dome resides on its outer surface.
II. The dome potential rises as more charge is accumulated.
III. The belt must be a good metal conductor for charge transport.

33. A potential function in a region is , where is in and are in . The electric field vector is:

34. For slow movement of a charge in an electrostatic field, the external work is equal to:

35. A basic capacitor consists of two conducting plates separated by an insulating medium. When the capacitor is charged from an initially neutral state, the plates usually carry:

36. The exact expression for a dipole potential is based on:

37. A graph is described as follows.

What physical conclusion follows from this reference-level change?

38. For two regions, the potential functions are:
Region P:
Region Q:
Here is in and is in . The comparison of field magnitudes is:

39. The capacitance of a conductor or capacitor is best understood as:

40. In the network of two parallel branches, Branch P has a single capacitor and Branch Q has in series with . The network is across . The total energy stored is:

41. At a point away from a point charge in vacuum, the potential is . What is the source charge? Take .

42. The energy stored in a charged capacitor can be written as:

43. The negative sign in means that:

44. A dipole of moment is placed in a uniform electric field of . At , the torque magnitude is nearest to:

45. When a charge moves slowly from to , where and , the external work is:

46. The far-field potential of a dipole changes sign when a point crosses the equatorial plane because:

47. For motion of a charge slowly around a closed path in an electrostatic field, its change in potential energy over the complete path is:

48. The row that correctly compares torque and potential energy of a dipole in a uniform electric field is:

49. A conducting spherical shell of radius is isolated and initially neutral. A charge is placed at the centre of its cavity. Taking , the potential of the shell is:

50. A point has potential with infinity as the zero reference. The external work needed to bring a positive test charge slowly from infinity to is: