A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference V across the plates. If the separation between the plates is doubled, the electrical energy stored in the capacitor will be

if we double the distance the energy stored will be doubled also

Explanation:

The energy stored in a capacitor is given as

Energy stored = 1/2 (cv²)

Or

= 1/2 (Qv)

Where c = capacitance

Q = charge

But the electric field is expressed as

E = v/d

where v = voltage

d = distance

v=Ed

Substituting into any equation above say

Energy stored = 1/2 (Qv)

Substituting v=Ev

Energy stored = 1/2 (QEd)

From the equation above it shows that if we double the distance The energy stored will be doubled also