Formula Capacitor Electrical energy Capacitance Voltage
$$W_{\text e} ~=~ \frac{1}{2} \, C \, U^2$$ $$W_{\text e} ~=~ \frac{1}{2} \, C \, U^2$$
Electrical energy
$$ W_{\text e} $$ Unit $$ \mathrm{J} $$ Energy stored, for example, in the electric field of a plate capacitor. The formula also applies to other charged bodies to which a capacitance \(C\) can be assigned.
Capacitance
$$ C $$ Unit $$ \mathrm{F} = \frac{ \mathrm{C} }{ \mathrm{V} } $$ Capacitance is a measure of how well a body can store charge. For example, how well the plate capacitor can store charge on its plates.
Voltage
$$ U $$ Unit $$ \mathrm{V} $$ Voltage, for example, between the electrodes of a plate capacitor.