Electric Charges and Fields Class 12 Physics MCQs Pdf
37. Why does a nylon or plastic comb get electrified on combing or rubbing but a metal spoon does not?
Answer/Explanation
Answer:
Explaination:
The charge on a metal spoon discharges through our body to the ground as both
are conductors. But when a nylon or plastic comb is rubbed, due to the friction
its acquires a negative (-ve) charge, which stays on it as it is an insulator.
38. Two metallic spheres having same shape and size, but one of Cu and other of Al, are both placed in an identical electric field. In which metallic sphere will more charge be induced?
Answer/Explanation
Answer:
Explaination:
Same charge will be induced on both the spheres. As the dielectric constant K =
oo for metals and the induced charge is given by q’ =
\(=-q\left(1-\frac{1}{K}\right)\).
39. What causes the charging of an object?
Answer/Explanation
Answer:
Explaination:
When an object looses or gains electrons by friction/conduction/induction, then
it is charged.
40. What does the additive nature of electric charge mean?
Answer/Explanation
Answer:
Explaination:
It means an electric charge is a scalar quantity and is added like algebraic
numbers.
41. When does a charged ring behave as a point charge?
Answer/Explanation
Answer:
Explaination:
When the radius of ring is much smaller than the distance under consideration.
42. Two insulated charged copper spheres A and B of identical size have charges qA and qB respectively. A third sphere C of the same size but uncharged is brought in contact with the first and then in contact with the second and finally removed from both. What are the new charges on A and B1 [Chennai 2019, Foreign 2011]
Answer/Explanation
Answer:
Explaination:
43. What does q1 + q2 = 0 signify?
Answer/Explanation
Answer:
Explaination:
q1 + q2 = 0
⇒ q1 = – q2
∴ q1 and qq2 are the two charges of an electric dipole.
44. What is the cause of quantisation of electric charge?
Answer/Explanation
Answer:
Explaination:
The minimum charge that is stable, is charge of an electron. Since, electrons
are transferred from one object to another, therefore, electric charge is said
to be quantised.
45. What do you mean by conservative nature of the electric force?
Answer/Explanation
Answer:
Explaination:
The electric force is conservative in nature, because the work done by it in
moving a charge is path independent.
46. If a body contains n1 electrons and n2 protons, then what will be the total amount of charge on the body?
Answer/Explanation
Answer:
Explaination:
Electric charge on n1 electrons = – n1e and electric
charge on n2 protons = + n2e Therefore, the total charge =
(n2 – n1)e.
47. What is the limitation of Coulomb’s law?
Answer/Explanation
Answer:
Explaination: It is applied only for point charges.
48. What does e(absolute permittivity) signify?
Answer/Explanation
Answer:
Explaination: It is a measure of the degree to which a medium can resist the
movement of charges.