Electric Charges and Fields Mock Test – Class 12 Physics

1. Study the table for a fixed pair of charges in the same medium and identify the row that does not follow Coulomb proportionality.

2. A charge is placed at the centre of a square. Four identical positive charges are fixed at the four corners. If the centre charge is removed, the electric field at the centre due to the four corner charges is

3. A negatively charged rod is brought near the cap of a neutral electroscope without touching it. The leaves diverge during the approach, but the electroscope is not earthed. This observation is best explained by

4. A non-uniformly charged rod is divided mentally into very small pieces. The use of in is helpful because

5. A dipole of moment is in a uniform electric field . It rotates slowly from to . The change in potential energy is

6. A statement says, “A dielectric medium increases the Coulomb force because is placed in the formula.” The suitable correction is that the medium

7. A student writes . This value represents

8. A square surface of side has area vector . A uniform field makes with . If the surface is then rotated so that the angle becomes , the change in flux is

9. A small pillbox Gaussian surface is drawn across the surface of a charged conductor in electrostatic equilibrium. The field just outside is , the surface charge density is , and the field inside the conductor is zero. Gauss’s law gives

10. Study the Gauss-law table and identify the row that is incorrect.

11. Consider the following statements about electric charge.
I. Electric charge can be positive or negative.
II. The sign of charge gives a fixed spatial direction.
III. A neutral body has zero net charge.
IV. Like charges repel each other.
The supported set is

12. For an infinite uniformly charged plane sheet with surface charge density , the electric field is directed

13. Three identical isolated conducting spheres have initial charges , , and . First, sphere P touches sphere Q and separates. Then sphere P touches sphere R and separates. The final charge on sphere P is

14. In the derivation of the point-charge field using Gauss’s law, the step is valid because

15. Study the constant-symbol table and identify the mismatched row.

16. Two charges and are fixed on a line. At any point between them, the electric field contributions due to the two charges are

17. A charged conductor touches a neutral conductor. The final charge acquired by the neutral conductor depends on the

18. A graph of versus for a dipole in a uniform field is based on . The graph has a maximum at

19. In the arrangement of two large parallel sheets with surface charge densities and , the electric field in the region exactly between the sheets is

20. A record of a rubbing experiment is shown below.

The row that does not fit ordinary charging by friction is

21. The sign acquired by a body during rubbing depends mainly on

22. A student compares , , and for a Gaussian surface. The correct statement is

23. If the separation between two fixed point charges is tripled, while the charges and medium are unchanged, the magnitude of Coulomb force becomes

24. The orientation for a dipole in a uniform electric field is called stable equilibrium because

25. Study the comparison table for a far electric dipole field and identify the mismatched row.

26. Study the table for a dipole in a uniform electric field and identify the row that needs correction.

27. Charges and are fixed apart in vacuum. What is the magnitude of the electric field at the midpoint between them? Take .

28. Study the table for two charges on the -axis. In each case, is at , is at , and . Identify the row with a mismatched force direction for .

29. Charges , , and a small positive charge lie on a straight line. The charge is at , is at , and is placed at between them so that the net force on is zero. The value of is

30. A surface is tilted so that the electric field makes an angle with the plane of the surface. The angle to be used in is

31. Two identical isolated conducting spheres initially carry and . After touching and separating, one of them is touched to a third identical neutral sphere and then separated. The final charge on the first sphere after the second contact is

32. Assertion: In charging by contact, a neutral conductor can acquire the same sign of charge as the charged conductor that touches it.
Reason: During contact, charge can flow and redistribute through the conducting connection.

33. Two charges are fixed at the ends of a line segment. The force direction is being decided before calculating the force magnitude. The most reliable first step is to

34. A claim says, “Induction and polarization are exactly the same because both begin with charge separation.” The best evaluation is that the claim is

35. The area vector of a plane surface is drawn

36. A dipole of moment is in a uniform electric field . At an angle , its torque magnitude is and potential energy is . If and , then equals

37. The order of operations matters in induction. For a conductor to be left charged using a nearby positive rod, the suitable sequence is

38. Read the case below.

The magnitude of the net electric force on the charge is

39. A charge distribution has spherical symmetry, but the charge enclosed by a spherical Gaussian surface of radius changes with . The correct Gauss-law strategy is to use

40. A negatively charged rod is held near a neutral metal sphere on an insulating stand. The sphere is then connected briefly to earth while the rod remains nearby. During earthing, electrons tend to flow

41. The linear charge density of a charged wire is defined as charge per unit

42. A far dipole field is compared with the field of a single point charge. The dipole field decreases faster with distance because it varies as

43. A charge is placed at the centre of a spherical Gaussian surface of radius . The electric field magnitude on the surface is

44. A pair of charges experiences a force in vacuum. When the space between them is filled with a dielectric of constant , the force becomes

45. A charged conducting plane surface in electrostatic equilibrium has surface charge density . Just outside the conductor, the electric field is

46. A charged body is brought near a neutral conductor, and the conductor moves slightly toward it. This motion should not be confused with charge movement because

47. Study the table for Gauss-law applications and identify the row with the wrong distance dependence.

48. A body has both charge and mass, but a nearby neutral massive object exerts gravitational attraction while a nearby charged object exerts electrostatic force. The property paired correctly with the force is

49. In electrostatics, electric charge is treated as a scalar quantity, while electrostatic force is treated as

50. The dimensional formula of can be obtained from . Taking charge dimension as , the dimension of is