Question

25. A potential difference V is applied to n identical capacitors connected in parallel. These capacitors are
now connected in series without disturbing their charges. The potential difference of the capacitors
connected in series is
(b) nV
(c) nềv
(d)(n-1) V​

Answer 1

Answer:

Let capacitance of each capacitor is C.

N capacitors are joined in parallel combination,

so, Ceq = C + C + C + C ..... N times = NC

total charge = equivalent capacitance × potential

= NC × v

now, when all capacitors are joined in series combination.

so, 1/Ceq = 1/C + 1/C + 1/C + ... N times

Ceq' = C/N

Let new potential across the combination is V'

so, charge = (C/N)V'

according to conservation of energy,

U_{parallel}=U_{series}U

parallel

=U

series

or, 1/2 Ceq v² = 1/2 Ceq' V'²

or, (NC)v² = (C/N)V'²

or, v²/N² = V'²

or, V' = v/N

hence, when the capacitors are joined in series potential v/N but energy of the combination will be same.