MCQs On Electric charge and Fields For NEET pdf

Multiple Choice Questions On Electric charge and Fields with answers

1. At a distance r, two equal charges are kept and they exert a force F on each other. What is the force acting on each charge, if the distance between them is doubled and charges are halved?

(a) F/4

(b) 4 F

(c) F/16

(d) F/8

Answer: C

2. In nature, the electric charge of any system is always equal to__________

(a) half integral multiple of the least amount of

charge

(b) zero

(c) square of the least amount of charge

(d) integral multiple of the least amount of charge

Answer: D

3. Consider a neutral conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then__________

(a) negative and distributed uniformly over its surface.

(b) negative and appears only at the point on the

sphere closest to the point charge

(c) negative and distributed non-uniformly over its entire surface of the sphere

(d) zero

Answer: D

4. Two point charges placed at a distance ‘r’ in air exert a force ‘F’. The distance at which they exert same force when placed in a certain medium(dielectric constant K) is _______

(a) rK 

(b) r/K

(c) r K 

(d) r √K

Answer:C

5. What equal charges should to be placed one earth and moon to neutralize their gravitational attraction ? (mass of earth = 1025 kg, mass of moon= 1023 kg)

(a) 8.6 × 10¹³ C 

(b) 6.8 × 10²⁶ C

(c) 8.6 × 10³C

(d) 9 × 10⁶ C

Answer: C

6. When a plastic comb is passed through dry hair, the charge acquired by the comb is__________

(a) always negative

(b) always positive

(c) sometimes negative

(d) none of the above

Answer: A

7. The value of absolute permittivity of free space is______

(a) 9×10-⁹C-²Nm²

(b) 9×10⁹C-²Nm²

(c) 8.85×10-¹² C²N-¹m-²

(d) 8.85×10¹² C²Nm-²

Answer: C

8. For a dipole, the value of each charge is 10–10 stat coulomb and their separation is 1Å, then its dipole moment is _______

(a) one debye 

(b) 2 debye

(c) 10–3 debye 

(d) 3 × 10–20 debye

Answer: A

9. The electric potential and field at a point due to an electric dipole are proportional to _____

(a) r, r–¹ 

(b) r–¹, r–² 

(c) r–², r–3

(d) r–², r–²

Answer: C

10. When an electric dipole p r is kept in a uniform electric field Er then for what value of angle between p r and E r will the torque be maximum ?

(a) 90° 

(b) 0° 

(c) 180° 

(d) 45°

Answer: A

11. What will be the ratio of electric field at a point on the axis and an equidistant point on the equatorial line of a dipole________

(a) 1 : 2

(b) 2 : 1 

(c) 4 : 1 

(d) 1 : 4

Answer: B

12. For a dipole q = 2 × 10–⁶ C ; d = 0.01m; find the maximum torque on the dipole if

E = 5 × 10⁵N/C 

(a) 1 × 10–³ Nm–¹

(2) 10 × 10–³ Nm–¹

(3) 10 × 10–³ Nm 

(4) 1 × 10–⁴ Nm

Answer: C

13. Electric field due to a single charge is_____________

(a) assymetric

(b) cylindrical symmetric

(c) spherical symmetric

(d) none of the above

Answer: A

14. Electric field due to an electric dipole is____________

(a) spherical symmetric

(b) cylindrical symmetric

(c) assymetric

(d) none of the above

Answer: A

15. charged conducting sphere has diameter 2.4 m and surface charge density 10 µC/m²Electric flux passing through its surface will be _________

(a) 2 × 10⁷ Nm2/C 

(b) 16 × 10⁷ Nm2/C

(c) 1 × 10⁶ Nm2/C 

(d) 2.2 × 10⁸Nm2/C

Answer: A

16. A straight cylindrical wire of infinite length produces electric field of strength 9 × 10⁴ ​N/C at a distance of 10 cm. Linear charge density of the wire is_________

(a) 0.1 µC/m

(b) 0.5 µC/m

(c) 50 µC/m

(d) 10 µC/m

Answer: B

17. For a uniformly charged sphere, the electric field from its centre _______

(a) increases linearly upto the surface

(b) decreases linearly upto the surface

(c) remains zero upto the surface

(d) first increases and then decreases upto the surface

Answer: A

18. The dimensional formula of electric flux is________

(a) L³MT³I¹

(b) L²MT−³I¹

(c) L³MT−³I−¹

(d) L−3³MT−3I

Answer: C

19. What is the value of minimum force acting between two charges placed at 1m apart from each other__________

(a) Ke

(b) Ke/4

(c) Ke2

(d) Ke2/2

Answer: C

20. An electron of mass me initially at rest moves through a certain distance in a uniform electric field in time t¹. A proton of mass mp also initially at rest takes time t² to move through an equal distance in this uniform electric field. Neglecting the effect of gravity, the ratio of t²/t¹ is nearly equal to______

(a) 1 

(b) (mp/me)½

(c) (me/mp)½ 

(d) 1836

Answer: B

21. There is a uniform electric field of strength 10³ ​V/m along y–axis. A body of mass 1 g and charge 10–⁶C is projected into the field from origin along positive x–axis with a velocity 10 m/s. Its speed in m/s after 10 s is :- (neglect gravitation)

(a) 10 

(b) 5 √2

(c) 10√ 2 

(4) 2

Answer: C

22. When a plastic comb is passed through dry hair, the charge acquired by the comb is___________

(a) always negative

(b) always positive

(c) sometimes negative

(d) none of the above

Answer:A

23.The cause of quantization of electric charge is___________

(a) transfer of electrons

(b) transfer of protons

(c) transfer of integral number of electrons

(d) none of the above

Answer: C

24. At a given distance from the centre of electric dipole, field intensity on axial line is k times the field intensity on equatorial line, where k =

(a) 2

(b) 4

(c) 1

(d) 3

Answer: B

25. The number of electric lines of force radiating from a closed surface in vacuum is 1.13×1011. The charge enclosed by the surface is__________

(a) 1C

(b) 1μC

(c) 0.1C

(d) 0.1μC

Answer: A