Class XII- Electric Charges and Fields MCQs Question Bank

 CLASS XII

MULTIPLE CHOICE QUESTIONS

CHAPTER 1

Electric Charges and Fields

1. A point charge causes an electric flux of −2×104Nm2C-1 to pass through a spherical Gaussian surface of 8.0 cm radius, centred on the charge. The value of the point charge is : (𝟄0= 8.85 x 10-12 C2 N-1m-2) (JEE MAIN 2025)

1. 17.7 x 10-8 C

2. -17.7 x 10-8 C

3. 15.7 x 10-8 C

4. -15.7 x 10-8 C

2. An electric dipole is placed at a distance of 2 cm from an infinite plane sheet having positive charge density σo Choose the correct option from the following.(JEE MAIN 2025)

1. Torque on dipole is zero and net force is directed away from the sheet

2. Potential energy of dipole is minimum and torque is zero

3. Potential energy and torque both are maximum

4. Torque on dipole is zero and net force acts towards the sheet

3. Five charges +q, +5q, -2q, +3q and -4q are situated as shown in the figure. The electric flux due to this configuration through the surface S is. (JEE MAIN 2024)

1. q/𝟄0

2. 3q/𝟄0

3. 5q/𝟄0

4. 4q/𝟄0

4. Two identical conducting spheres P and S with charge Q on each, repel each other with a force  16 N. A third identical uncharged conducting sphere R is successively brought in contact with the two spheres. The new force of repulsion between P and S is : (JEE MAIN 2024)

1. 1 N

2. 6 N

3. 12 N

4. 4 N

5. C1 and C2 are two hollow concentric cubes enclosing charges 2Q and 3Q respectively as shown in figure. The ratio of electric flux passing through C1 and C2 is :(JEE MAIN 2024)

1. 3:2

2. 5:2

3. 2:5

4. 2:3

6. The electrostatic potential due to an electric dipole at a distance ‘r’ varies as : (JEE MAIN 2024)

1. 1/ r3

2. 1/ r

3. 1/ r2

4. r

7. Graphical variation of electric field due to a uniformly charged insulating solid sphere of radius R, with distance r from the centre O is represented by: (JEE MAIN 2023)

1. b.

    c. d.

8. A  10 μC charge is divided into two parts and placed at  1 cm distance so that the repulsive force between them is maximum. The charges of the two parts are: (JEE MAIN 2023)

1. 9 μC, 1 μC

2. 5 μC, 5 μC

3. 8 μC, 2 μC

4. 7 μC, 3 μC

9. Two charges each of magnitude  0.01 C and separated by a distance of  0.4 mm constitute an electric dipole. If the dipole is placed in an uniform electric field E of 10 dyne/C making 300 with E the magnitude of torque acting on dipole is: (JEE MAIN 2023)

1. 4.0 x 10-10 Nm

2. 1.5 x 10-9 Nm

3. 1.0 x 10-8 Nm

4. 2.0 x 10-10 Nm

10. Two identical metallic spheres A and B when placed at a certain distance in air repel each other with a force of F. Another identical uncharged sphere C is first placed in contact with A and then in contact with B and finally placed at the midpoint between spheres A and B. The force experienced by sphere C will be: (JEE MAIN 2023)

1. 3F/2

2. 3F/4

3. F

4. 2F

11. A thin plastic rod is bent to a circular ring of radius R. It is uniformly charged with charge density λ. The magnitude of the electric field at its centre is: (CBSE 2024)

1. λ/(2𝟄0R)

2. 0

3. λ/(4π𝟄0R)

4. λ/(4𝟄0R)

12. Two charged particles P and Q, having the same charge but different masses mp and mq, start from rest and travel equal distances in a uniform electric field E in time tp and tq respectively. Neglecting the effect of gravity, the ratio (tp / tq ) is: (CBSE 2024)

13. Coulomb force F versus (1/r2) graphs for two pairs of point charges (q1 and q2) and (q2 and q3) are shown in the figure. The ratio of charges (q1 / q3) is: (CBSE 2024)

1. √3

2. 1/√3

3. 3

4. 1/3

14. An isolated conductor, with a cavity, has a net charge +Q. A point charge +q is inside the cavity. The charges on the cavity wall and the outer surface are respectively : (CBSE 2024)

1. 0 and Q

2. -q and Q-q

3. -q and Q+q

4. 0 and Q-q

15. Two identical small conducting balls B1 and B2 are given -7pC and +4pC charges respectively. They are brought in contact with a third identical ball B3 and then separated. If the final charge on each ball is -2pC, the initial charge B3 was: (CBSE 2024)

1. -2pC

2. -3pC

3. -5pC

4. -15pC

16. Coulomb force F versus (1/r2) graphs for two pairs of point charges (q1 and q2) and (q2 and q3) are shown in the figure. The charge q2 is positive and has least magnitude then: (CBSE 2024)

1. q1 > q2 > q3

2. q1 > q3 > q2

3. q3 > q2 > q1

4. q3 > q1 > q2

17. An infinite long straight wire having a charge density λ is kept along y’y axis in the X-Y plane. The coulomb force on a point charge q at a point P(x,0) will be: (CBSE 2024)

18. A point charge situated at a distance ‘r’ from a short electric dipole on its axis, experiences a force F. If the distance of the charge is ‘2r’, the force on the charge will be: (CBSE 2023)

1. F/16

2. F/8

3. F/4

4. F/2

19. An electron experiences a force (1.6 x 10-16 N) in an electric field. The electric field is: (CBSE 2023)

20. Two charges q1 and q2 are placed at the centres of two spherical conducting shells of radius r1 and r2 respectively. The shells are arranged such that their centres are d [ > (r1 + r2)] distance apart. The force on q2 due to q1 is : (CBSE 2023)

21. The total flux through the faces of the cube with side of length a if a charge q is placed at corner A of the cube is:

a. q/8𝟄0

b.q/4𝟄0

c. q/2𝟄0

d. q/𝟄0

22. Which of the following figures represent the electric field lines due to a single negative charge?

23. A body is negatively charged means:

1. It has only negative charges

2. Positive charges are neutralised by negative charges

3. The quantity of negative charge present is more than the quantity of positive charges

4. The positive charges are displaced from their original positions

24. A point positive charge is brought near an isolated conducting sphere in Figure. The electric field is best given by: (NCERT Exemplar)

1. Fig (i)

2. Fig (ii)

3. Fig (iii)

4. Fig (iv)

25. The electric flux through the surface: (NCERT Exemplar)

1. In Figure (iv) is the largest

2. In Figure (iii) is the least

3. In Figure (ii) is the same as Figure (iii) but is smaller than Figure (iv)

4. Is the same for all the figures

26. Figure shows electric field lines in which an electric dipole p is placed as shown. Which of the following statements is correct? (NCERT Exemplar)

 

1. The dipole will not experience any force

2. The dipole will experience a force towards right

3. The dipole will experience a force towards left

4. The dipole will experience a force upwards

27. A point charge +q is placed at distance d from an isolated conducting plane. The field at a point P on the other side of the plane is: (NCERT Exemplar)

1. Directed perpendicular to the plane and away from the plane

2. Directed perpendicular to the plane but towards the plane

3. Directed radially away from the point charge

4. Directed radially towards the point charge

28. If over a surface, then: (NCERT Exemplar)

1. The electric field inside the surface and on it is zero

2. All charges must necessarily be outside the surface

3. The number of flux lines entering the surface must be equal to the number of flux lines leaving it

4. Both (b) and (c)

29. The electric flux through a closed gaussian surface depends upon: (CBSE 2020)

1. Net charge enclosed and permittivity of the medium

2. Net charge enclosed, permittivity of the medium and the size of the Gaussian surface

3. Net charge enclosed only

4. Permittivity of the medium only

30. The electric flux emerging out from 1C charge is: (CBSE 2020)

1. 1/𝟄0

2. 4π

3. 4π/𝟄0

4. 𝟄0

ANSWER KEY

1	2	3	4	5	6	7	8	9	10
B	B	D	B	C	C	D	B	D	B
11	12	13	14	15	16	17	18	19	20
B	C	C	B	C	A	B	A	B	A
21	22	23	24	25	26	27	28	29	30
A	B	C	C	D	C	A	D	A	A