Electric Charges and Fields Class 12 Physics MCQs Pdf
49. Define 1 coulomb (1 C) of electric charge.
Answer/Explanation
Answer:
Explaination:
One coulomb is that charge, when placed in vacuum at a distance of one metre
from an equal and similar charge, would repel it with a force of 9 ×
109 N.
50. Write two properties of an electrostatic force.
Answer/Explanation
Answer:
Explaination:
(a) It is conservative in nature.
(b) It depends on medium between the two charges.
51. Is the force acting between two point electric charges qx and q2 kept at some
distance apart in air, attractive or repulsive when
(i) q1q2 > 0
(ii) q1q2 < 0?
Answer/Explanation
Answer:
Explaination:
(i) When q1q2 > 0, force is repulsive.
(ii) When q1q2 < 0, force is attractive.
52. The force on an electron kept in an electric field in a particular direction is
F. What will be the magnitude and direction of the force experienced by a proton
kept at the same point in the field? Mass of the proton is about 1836 times the mass
of the electron.
Answer/Explanation
Answer:
Explaination: Same in magnitude and opposite in the direction as F = e.E
53. How does the coulomb force between two point charges depend upon the dielectric constant of the intervening medium?
Answer/Explanation
Answer:
Explaination:
Coulomb force is inversely proportional to the dielectric constant of the
intervening medium.
54. State principle of superposition of forces.
Answer/Explanation
Answer:
Explaination:
Net force experienced by any charge in a group of charges is the vector sum of
the forces acting on it due to rest of the charges of the group.
55. Define the dielectric constant of a medium. What is its unit? [Delhi 2011C]
Answer/Explanation
Answer:
Explaination:
Dielectric constant of a medium is defined as the ratio of the force between two
charges placed a certain distance apart in vacuum to the force between the same
two charges placed the same distance apart in the medium. It has no units.
56. Two equal balls having equal positive charge q coulombs are suspended by two insulating strings of equal length. What would be the effect on the force when a plastic sheet is inserted between the two? [AI 2014]
Answer/Explanation
Answer:
Explaination:
Electric force will reduce as plastic is an insulator. The force between the two
charges will reduce by 1/K, where K is the dielectric constant of plastic.
57. Two electric field lines never cross each other. Why?
Answer/Explanation
Answer:
Explaination:
Two field lines can never cross each other. If they did, the field at the point
of intersection will not have a unique direction, which is absurd.
58. Draw the electric field lines due to apoint charge
(i) Q > 0 and (ii) Q< 0.
Answer/Explanation
Answer:
Explaination:
(i) Q > 0 (ii) Q < 0
59. Why do the electric field lines not form any closed loops?
Answer/Explanation
Answer:
Explaination:
Because they originate from positive (+ve) charge and terminate at negative
(-ve) charge.
60. Draw electric field lines for a system of two charges q1 and
q2 such that
(i) q1q2 >0; q1>q2>0
(ii) q1 q2 <0; q1 > |-q2| < 0,
|q1|> |-q2|
Answer/Explanation
Answer:
Explaination:
