Energy Stored in a Capacitor
The energy stored on a capacitorcan be calculated from the equivalent expressions:
The energy stored on a capacitor can be expressed in terms of the work done by the battery.
Voltage represents energy per unit charge,
so the work to move a charge element dq from the negative plate to the positive plate is equal to V dq,
where
V is the voltage on the capacitor.
The voltage V is proportional to the amount of charge which is already on the capacitor.
Element of energy stored