8.4: Energy Stored in a Capacitor
The expression in Equation 8.4.2 8.4.2 for the energy stored in a parallel-plate capacitor is generally valid for all types of capacitors. To see this, consider any uncharged capacitor (not necessarily a parallel-plate type). At some instant, we connect it across a battery, giving it a potential difference V = q/C V = q / C between its plates.