Electric Charges and Fields MCQs Mock Test of Class 12th Physics

Welcome to your Electric Charges and Fields MCQs Mock Test of Class 12th Physics

1.

Q.1. The unit of electric dipole moment is

(a) newton

(b) coulomb

(c) farad

(d) debye

2.

Q.2. Consider a region inside which, there are various types of charges but the total charge is zero. At points outside the region

(a) the electric field is necessarily zero.

(b) the electric field is due to the dipole moment of the charge distribution only.

(c) the dominant electric field is inversely proportional to r3, for large r (distance from origin).

(d) the work done to move a charged particle along a closed path, away from the region will not be zero.

3.

Q.3. The surface considered for Gauss’s law is called

(a) Closed surface

(b) Spherical surface

(c) Gaussian surface

(d) Plane surface

4.

Q.4. The SI unit of electric flux is

(a) N C-1 m-2

(b) N C m-2

(c) N C-2 m2

(d) N C-1 m2

5.

Q.5. Which of the following statements is not true about Gauss’s law?

(a) Gauss’s law is true for any closed surface.

(b) The term q on the right side side of Gauss’s law includes the sum of all charges enclosed by the surface.

(c) Gauss’s law is not much useful in calculating electrostatic field when the system has some symmetry.

(d) Gauss’s law is based on the inverse square dependence on distance contained in the coulomb’s law

6.

Q.6. Four charges are arranged at the comers of a square ABCD, as shown. The force on the charge kept at the centre O is

(a) zero

(b) along the diagonal AC

(c) along the diagonal BD

(d) perpendicular to side AB

7.

Q.7. Calculate the flux through the cuboid shown in the figure for E = E0 y j :-

(a) E0abc

(b) E0abd

(c) E0abcd

(d) Zero

8.

Q.8. Charge is the property associated with matter due to which it produces and experiences

(a) electric effects only

(b) magnetic effects only

(c) both electric and magnetic effects

(d) None of these

9.

Q.9. Charge is

(a) transferable

(b) associated with mass

(c) conserved

(d) All of these

10.

Q.10. A body is positively charged, it implies that

(a) there is only positive charge in the body.

(b) there is positive as well as negative charge in the body but the positive charge is more than negative charge

(c) there is equal positive and negative charge in the body but the positive charge lies in the outer regions

(d) negative charge is displaced from its position

11.

Q.11. On rubbing, when one body gets positively charged and other negatively charged, the electrons transferred from positively charged body to negatively charged body are

(a) valence electrons only

(b) electrons of inner shells

(c) both valence electrons and electrons of inner shell

(d) yet to be established

12.

Q.12. Which of the following is the best insulator?

(a) Carbon

(b) Paper

(c) Graphite

(d) Ebonite

13.

Q.13. If a body is negatively charged, then it has.....

(a) excess of electrons

(b) excess of protons

(c) deficiency of electrons

(d) deficiency of neutrons

14.

Q.14. When a body is charged by induction, then the body....

(a) becomes neutral

(b) does not lose any charge

(c) loses whole of the charge on it

(d) loses part of the charge on it

15.

Q.15. On charging by conduction, mass of a body may

(a) increase

(b) decreases

(c) increase or decrease

(d) None of these

16.

Q.16. Quantisation of charge implies

(a) charge cannot be destroyed

(b) charge exists on particles

(c) there is a minimum permissible charge on a particle

(d) charge, which is a fraction of a coulomb is not possible.

17.

Q.17. If an object possesses an electric charge, it is said to be electrified or … A … When it has no charge, it is said to be … B … Here, A and B refer to

(a) charged, neutral

(b) neutral, charged

(c) discharged, charged

(d) active, reactive

18.

Q.18. A positively charged rod is brought near an uncharged conductor. If the rod is then suddenly withdrawn, the charge left on the conductor will be

(a) positive

(b) negative

(c) zero

(d) cannot say

19.

Q.19. Two spheres A and B of exactly same mass are given equal positive and negative charges respectively. Their masses after charging

(a) remains unaffected

(b) mass of A > mass of B

(c) mass of A < mass of B

(d) Nothing can be said

20.

Q.20. When a comb rubbed with dry hair attracts pieces of paper. This is because the

(a) comb polarizes the piece of paper

(b) comb induces a net dipole moment opposite to the direction of field

(c) electric field due to the comb is uniform

(d) comb induces a net dipole moment perpendicular to the direction of field

21.

Q.21. When some charge is transferred to …A… it readily gets distributed over the entire surface of … A… If some charge is put on … B…, it stays at the same place. Here, A and B refer to

(a) insulator, conductor

(b) conductor, insulator

(c) insulator, insulator

(d) conductor, conductor

22.

Q.22. Quantisation of charge was experimentally demonstrated by

(a) Einstein’s photoelectric effect

(b) Frank-Hertz experiment

(c) Davisson and Germer experiment

(d) Millikan’s oil drop experiment

23.

Q.23. In annihilation process, in which an electron and a positron transform into two gamma rays, which property of electric charge is displayed?

(a) Additivity of charge

(b) Quantisation of charge

(c) Conservation of charge

(d) Attraction and repulsion

24.

Q.24. The law, governing the force between electric charges is known as

(a) Ampere’s law

(b) Ohm’s law

(c) Faraday’s law

(d) Coulomb’s law

25.

Q.25. Coulomb’s law is true for

(a) atomic distances (= 10–11 m)

(b) nuclear distances (= 10–15 m)

(c) charged as well as uncharged particles

(d) all the distances

26.

Q.26. The value of electric permittivity of free space is

(a) 9 × 109 NC2/m2

(b) 8.85 × 10–12 Nm2/C2 sec

(c)8.85 × 10–12 C2/Nm2

(d) 9 × 109 C2/Nm2

27.

Q.27. What happens when some charge is placed on a soap bubble?

(a) Its radius decreases

(b) Its radius increases

(c) The bubble collapses

(d) None of these

28.

Q.28. When a glass rod is rubbed with silk, it

(a) gains electrons from silk.

(b) gives electrons to silk.

(c) gains protons from silk.

(d) gives protons to silk.

29.

Q.29. In general, metallic ropes are suspended on the carriers taking inflammable materials. The reason is ...

(a) to control the speed of the carrier.

(b) to keep the centre of gravity of the carrier nearer to the earth.

(c) to keep the body of the carrier in contact with the earth.

(d) none of these.

30.

Q.30. Two charges q1 and q2 are placed in vacuum at a distance d and the force acting between them is F. If a medium of dielectric constant 4 is introduced around them, the force now will be

(a) F

(b) F/2

(c) F/4

(d) 4F

31.

Q.31. When 10^(14) electrons are removed from a neutral metal sphere , the charge on it becomes

A 16μC

B −16μ

C C 32μC

D −32μC

32.

Q.32. Two similar spheres having +Q and -Q charges are kept at a certain distance. F force acts between the two. If at the middle of two spheres, another similar sphere having +Q charge is kept, then it experiences a force in magnitude and direction as

(a) zero having no direction.

(b) 8F towards +Q charge.

(c) 8F towards -Q charge.

(d) 4F towards +Q charge.

33.

Q.33. A charge Q is divided into two parts of q and Q – q. If the coulomb repulsion between them when they are separated is to be maximum, the ratio of Q/q should be

(a) 2:1

(b) 1/2

(c) 4:1

(d) 1/4

34.

Q.34. Electric field lines provide information about

(a) field strength

(b) direction

(c) nature of charge

(d) all of these

35.

Q35. In annihilation process, in which an electron and a positron transform into two gamma rays, which property of electric charge is displayed?

(a) Additivity of charge

(b) Quantisation of charge

(c) Conservation of charge

(d) Attraction and repulsion

36.

Q36. Charge is the property associated with matter due to which it produces and experiences

(a) electric effects only

(b) magnetic effects only

(c) both electric and magnetic effects

(d) None of these

37.

Q.37. The electric field inside a spherical shell of uniform surface charge density is

(a) zero.

(b) constant, less than zero.

(c) directly proportional to the distance from the centre.

(d) none of the these

38.

Q38. The SI unit of electric flux is

(a) N C-1 m-2

(b) N C m-2

(c) N C-2 m2

(d) N C-1 m2

39.

Q39. Coulomb’s law is true for

(a) atomic distances (= 10–11 m)

(b) nuclear distances (= 10–15 m)

(c) charged as well as uncharged particles

(d) all the distances

40.

Q.40. The electric field intensity due to an infinite cylinder of radius R and having charge q per unit length at a distance air r (r > R) from its axis is

(a) directly proportional to r².

(b) directly proportional to r3.

(c) inversely proportional to r.

(d) inversely proportional to r².

41.

Q.41. Electric field lines provide information about

(a) field strength

(b) direction

(c) nature of charge

(d) all of these

42.

Q. 42. Two point charges + 8q and - 2q are located at x = 0 and x = L respectively . The location of a point on the x axis at which the net electric field due to these two point charges is zero is

a. L/4

b. 2 L

c. 4 L

d. B L

43.

Q.43. The magnitude of electric field intensity E is such that, an electron placed in it would experience an electrical force equal to its weight is given by

(a) mge

(b) mg/e

(c) e/mg

(d) e²g/m²

44.

Q.44. In Fig. (i) two positive charges q2 and q3 fixed along the y-axis, exert a net electric force in the +x direction on a charge q1 fixed along the x-axis. If a positive charge Q is added at (x, 0) in figure (ii), the force on q1 is

(a) shall increase along the positive x-axis.

(b) shall decrease along the positive x-axis.

(c) shall point along the negative x-axis.

(d) shall increase but the direction changes because of the intersection of Q with q2 and qy

45.

Q.45. Which of the following statement is correct? The electric field at a point is

(a) always continuous.

(b) continuous if there is a charge at that point.

(c) discontinuous only if there is a negative charge at that point.

(d) discontinuous if there is a charge at that point.

46.

Q.46. A point charge +q is placed at a distance d from an isolated conducting plane. The field at a point P on the other side of the plane is

(a) directed perpendicular to the plane and away from the plane.

(b) directed perpendicular to the plane but towards the plane.

(c) directed radially away from the point charge.

(d) directed radially towards the point charge.

47.

Q.47. Gauss’s law will be invalid if

(a) there is magnetic monopole.

(b) the inverse square law is not exactly true.

(c) the velocity of light is not a universal constant.

(d) none of these.

48.

Q.48. SI unit of permittivity of free space is

(a) Farad

(b) Weber

(c) C2N-1 m-2

(d) C2N-1 m-2

49.

Q.49. A charge Q is placed at the centre of the line joining two point charges +q and +q as shown in the figure. The ratio of charges Q and q is

(a) 4

(b) 1/4

(c) -4

(d) -1/4

50.

Q. 50. The force per unit charge is known as

(a) electric flux

(b) electric field

(c) electric potential

(d) electric current

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