Gravitation Mock Test – Class 11 Physics

1. In charging by friction, the two rubbed bodies usually acquire equal and opposite charges because

2. A point charge is outside a closed spherical surface. Some electric field lines due to this charge pass through the sphere. The net flux through the closed sphere due to this outside charge is

3. The unit of can be inferred from . If is in , charge is in , and distance is in , the unit of is

4. Assertion: The electric field at a point can be zero even when the point is near more than one charge.
Reason: Electric field is a vector quantity, so equal and opposite field contributions can cancel.

5. A uniform electric field crosses a plane surface of area vector . The electric flux through the surface is

6. A rectangular surface has area . It is placed in a uniform electric field such that the angle between and is . The electric flux is

7. 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

8. A charged metal sphere touches an identical neutral metal sphere and is then separated. The charging process involved here is mainly

9. For a curved surface in a non-uniform electric field, the electric flux is written as

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

11. A spherical Gaussian surface encloses a point charge at its centre. If the radius of the sphere is doubled, the total electric flux through the sphere becomes

12. A pair production event creates an electron of charge and a positron of charge . The total charge produced in this pair is

13. Two large parallel sheets carry and . A proton is released from rest between them. Its initial acceleration is

14. Three charges lie on the -axis. A charge at the origin experiences toward due to a charge on the left and toward due to a charge on the right. The net force on is

15. Study the table for electric field directions at point on the -axis. Identify the row that needs correction.

16. A point charge is placed at , and a point charge is placed at . The magnitude of the electric field at the origin due to the charge is . The electric field vector at the origin due to is

17. Charge is at the origin and charge is on the positive -axis. With , the sign of in makes the force on

18. The unit is most naturally associated with

19. Study the dipole statements below.
I. An electric dipole has zero net charge.
II. The dipole moment magnitude is charge magnitude multiplied by separation.
III. The dipole moment vector points from to .
IV. A dipole can have non-zero dipole moment even though its net charge is zero.
The supported statements are

20. A point charge is placed at the centre of a cube. By symmetry, the electric flux through one face of the cube is

21. Assertion: In electrostatic superposition, the net force can be zero even when individual forces are non-zero.
Reason: Vector forces can cancel when they have equal magnitudes and opposite directions.

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

23. In a uniform electric field directed toward the right, a small positive charge released from rest initially accelerates

24. Assertion: In standard charging by induction, the final charge on the conductor is opposite in sign to the inducing charge.
Reason: During the earthing step, electrons move in a direction decided by the inducing charge, while the inducing body does not touch the conductor.

25. At a far axial point of a dipole, the electric field is at distance . At a far equatorial point at distance from the same dipole, the field magnitude is

26. In electrostatics, the symbols and should not be confused because

27. At the centre of a square, a charge experiences forces due to four corner charges. The two charges at one diagonal are and , while the two charges at the other diagonal are and . The net force on is

28. A graph of electric field magnitude versus distance from an ideal infinite plane sheet is best represented as

29. A student writes that the field of an infinite line charge falls as because “all electric fields are inverse-square.” The correct response is that the line-charge field falls as

30. A particle of charge and mass is released from rest midway between two oppositely charged large plates separated by distance . The plates have surface charge densities and . Ignoring gravity, the speed of the particle just before reaching the negative plate is

31. Assertion: The electrostatic forces between two point charges have equal magnitudes even if the charges have unequal magnitudes.
Reason: The two forces form an action-reaction pair along the line joining the charges.

32. A uniformly charged thin spherical shell of radius carries total charge . For an outside point at distance from the centre, the electric field is the same as if

33. 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

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

35. A field-line sketch shows twice as many lines leaving charge P as leaving charge Q. If both charges are positive and the same drawing convention is used, the likely relation between their magnitudes is

36. In the pillbox derivation for an infinite plane sheet, the curved surface of the pillbox contributes zero flux because

37. When the separation of two fixed point charges changes from to , the force changes from to

38. A point charge is kept at the centre of a spherical Gaussian surface. The field is first found from Gauss’s law and then a charge is placed on the surface. The force on is

39. The scalar magnitude form of Coulomb’s law in vacuum is

40. In charging by induction, a charged rod is brought near a neutral conductor without touching it. The first effect inside the conductor is

41. Study the field-line descriptions and identify the one that is not acceptable for an electrostatic field.

42. A dipole moment points along . At a point on the equatorial line above the centre of the dipole, the net electric field is directed

43. A plane sheet with charge density produces field . If another identical positive sheet is placed parallel to it, the field on the outer side of the pair is

44. An insulating plastic strip is charged at one small region by rubbing. Compared with a metal strip, the charge on the plastic strip is more likely to remain near that region because

45. A uniformly charged thin wire of length carries total charge . Its linear charge density is

46. A dipole is placed in two different regions.

The row that needs correction is

47. A charged conductor is in electrostatic equilibrium. Just outside its surface, the electric field must be

48. A charge is at . Two charges on the same line exert forces on it: toward left and toward right. Taking right as positive, the vector net force is

49. A student writes . This value represents

50. Two identical conducting spheres are isolated from surroundings. Sphere P has charge , and sphere Q is neutral. They touch and are then separated. The charge on each sphere after separation is