The
plates of a parallel plate capacitor have an area of 90 cm2
each and are separated by 2.5 mm. The capacitor is charged by
connecting it to a 400 V supply.
(a) How
much electrostatic energy is stored by the capacitor?
(b) View
this energy as stored in the electrostatic field between the plates,
and obtain the energy per unit volume u.
Hence arrive at a relation between u
and the magnitude of electric field
E between
the plates.