Question

A parallel-plate capacitor having circular plates of radius R and separation d is held at a fixed potential difference by a battery. If the plates are moved closer together while they are held at the same potential difference

a. the amount of charge on each of them will increase.
b. the amount of charge on each of them will decrease.
c. the amount of charge on each of them will stay the same.
d. the energy stored in the capacitor increases.

Answer 1

C= relative permittivity X permittivity of free space X a/d

Q= C/V (where Q is charge and V is voltage)

Since C increases so does the amount of charge on the plates. The stored energy also increases because E= 1/2 CV^2

A and D are correct.