Electrostatic Potential and Capacitance Class 12 Physics MCQs Pdf
31. Dielectric constant for a metal is
(a) zero
(b) infinite
(c) 1
(d) 10
Answer
Answer: b
32. When air is replaced by a dielectric medium of constant K, the maximum force of
attraction between two charges separated by a distance
(a) increases K times
(b) remains unchanged
(c) decreases K times
(d) increases K-1 times
Answer
Answer: c
33. In a parallel plate capacitor, the capacity increases if
(a) area of the plate is decreased.
(b) distance between the plates increases.
(c) area of the plate is increased.
(d) dielectric constantly decreases.
Answer
Answer: c
34. A parallel plate air capacitor is charged to a potential difference of V volts.
After disconnecting the charging battery the distance between the plates of the
capacitor is increased using an insulating handle. As a result the potential
difference between the plates
(a) increases
(b) decreases
(c) does not change
(d) becomes zero
Answer
Answer: a
35. Two identical capacitors are joined in parallel, charged to a potential V,
separated and then connected in series, the positive plate of one is connected to
the negative of the other. Which of the following is true?
(a) The charges on the free plated connected to-gether are destroyed.
(b) The energy stored in ths system increases.
(c) The potential difference between the free plates is 2V.
(d) The potential difference remains constant.
Answer
Answer: c
36. A capacitor has some dielectric between its plates, and the capacitor is
connected to a dc source. The battery is now disconnected and then the dielectric is
removed, then
(a) capacitance will increase.
(b) energy stored will decrease.
(c) electric field will increase.
(d) voltage will decrease.
Answer
Answer: c
37. Two spherical conductors each of capacity C are charged to potential V and -V.
These are then connected by means of a fine wire. The loss of energy is
(a) zero
(b) \(\frac{1}{2}\)CV2
(c) CV2
(d) 2 CV2
Answer
Answer: c
38. Work done in taking an electron around a proton in a circular loop is zero. Should the proton necessarily be at the centre of the circular loop?
Answer/Explanation
Answer:
Explaination:
No, because electrostatic force is a conservative force, and work done by a
conservative force in a closed path is zero.
39. An uncharged insulated conductor A is brought near a charged insulated conductor B. What happens to charge and potential of 5?
Answer/Explanation
Answer:
Explaination:
Initially the potential of conductor B = V. When an uncharged conductor A is
brought near to the conductor B, then the charges will induce on A. If
-V1 is the potential due to the negative induced charge at A, and
V2 is the potential due to the positive induced charge, then
|-V1| > |V2| (as -ve charge is near to B).
∴ Net potential on B = V – V1 + V2, which is less
than V. But charge on B remains same.
40. While defining the electrostatic potential energy, why do we bring a unit positive charge from infinity?
Answer/Explanation
Answer:
Explaination:
Because, at infinity, the electrostatic forces are zero. Therefore, the
electrostatic potential energy is also zero.