MCQ Questions for Class 12 Physics Chapter 1 Electric Charges and Fields with Answers
Question 1. Which one of the following is the unit of electric field?
Answer: (d) N/C
Question 2. 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.
Answer: (b) gives electrons to silk.
Question 3. The surface considered for Gauss’s law is called
(a) Closed surface
(b) Spherical surface
(c) Gaussian surface
(d) Plane surface
Answer: (c) Gaussian surface
Question 7. 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
Answer: (c) both electric and magnetic effects
Question 8. 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
Answer: (c) Gauss’s law is not much useful in calculating electrostatic field when the system has some symmetry.
Question 9. Three charges + 3q + q and Q are placed on a st. line with equal separation. In order to maket the net force on q to be zero, the value of Q will be :
Answer: (a) +3q
Question 10. 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.
Answer: (c) to keep the body of the carrier in contact with the earth.
Question 11. Charge is
(b) associated with mass
(d) All of these
Answer: (d) All of these
Question 12. 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
Answer: (b) there is positive as well as negative charge in the body but the positive charge is more than negative charge
Question 13. A charge Q is placed at the centre of the line joining two point charges +q and +q . The ratio of charges Q and q is
Answer: (d) -1/4
Question 14. The force per unit charge is known as
(a) electric flux
(b) electric field
(c) electric potential
(d) electric current
Answer: (b) electric field
Question 15. Electric field lines provide information about
(a) field strength
(c) nature of charge
(d) all of these
Answer: (d) all of these
Question 16. 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
Answer: (d) N C-1 m2
Question 17. The unit of electric dipole moment is
Answer: (d) debye
Question 18. If an electric dipole is kept in a uniform electric field then resultant electric force on it is :
(a) always zero
(b) never zero
(c) depend upon capacity of dipole
Answer: (a) always zero
Question 19. The number of electron-taken out from a body to produce 1 coulomb of charge will be :
(a) 6.25 × 1018
(b) 625 × 1018
(c) 6.023 × 1023
Answer: (a) 6.25 × 1018
Question 20. The work done in rotating an electric dipole in an electric field:
(a) W = ME (1 – cos θ)
(b) W = ME tan θ
(c)W = ME sec θ
Answer: (a) W = ME (1 – cos θ)
Question 21. Electric field in a cavity of metal:
(a) depends upon the surroundings
(b) depends upon the size of cavity
(c) is always zero
(d) is not necessarily zero
Answer: (d) is not necessarily zero
Question 22. The dielectric constant of a metal is:
Answer: (c) ∞