The capacity of a capacitor is $4 \times 10^{-6} \, F$ and its potential is $100 \, V$. The energy released on discharging it fully will be ....... $J$.

Three plates $A, B, C$ each of area $50 \, cm^2$ have a separation of $3 \, mm$ between $A$ and $B$ and $3 \, mm$ between $B$ and $C$. The energy stored when the plates are fully charged is (as shown in the figure):

$A$ capacitor of capacitance $C$ has stored energy $W$ and charge $Q$. If the charge is increased to $2Q$,what will be the new stored energy?

If a $12 \ pF$ capacitor is connected to a $50 \ V$ battery,then the electrostatic energy stored in the capacitor is . . . . . . .

$A$ battery does $200 \, J$ of work in charging a capacitor. The energy stored in the capacitor is ......... $J$.

The energy required to charge a capacitor of $5\,\mu F$ by connecting a $d.c.$ source of $20\,kV$ is......$kJ$.