It is possible to view the
potential energy of the capacitor as ‘stored’ in the electric field between
the plates To see this, consider for simplicity, a parallel plate capacitor
[of area A (of each plate) and separation d between the plates] Energy stored in the capacitor
= 
2
2
0
1
(
)
2
2
Q
A
d
C
A
σ
ε
=
×
(2 70)
The surface charge density s is related to the electric field E between
the plates,
0
E
=εσ
(2