The energy of a charged capacitor is given by the expression (q = charge on the capacitor and C = capacity of capacitor

• A

  $\frac{{\mathrm{q}}^2}{2\mathrm{C}}$

• B

  $\frac{{\mathrm{q}}^2}{\mathrm{C}}$

• C

  $2 \mathrm{q} \mathrm{C}$

• D

  $\frac{\mathrm{q}}{2{\mathrm{C}}^2}$