If the charge on the capacitor is increased by $2 \text{ C}$, the energy stored in it increases by $21 \%$. The original charge on the capacitor is (in $\text{ C}$)

$A$ $40 \, \mu F$ capacitor in a defibrillator is charged to $3000 \, V$. The energy stored in the capacitor is sent through the patient during a pulse of duration $2 \, ms$. The power delivered to the patient is ...... $kW$.

The plates of a parallel plate capacitor have an area of $90 \,cm^{2}$ each and are separated by $2.5 \,mm$. The capacitor is charged by connecting it to a $400 \,V$ supply.
$(a)$ How much electrostatic energy is stored by the capacitor?
$(b)$ View this energy as stored in the electrostatic field between the plates,and obtain the energy per unit volume $u$. Hence arrive at a relation between $u$ and the magnitude of electric field $E$ between the plates.

When a parallel plate capacitor is fully charged by a battery,the potential difference between the two plates becomes equal to the electromotive force $(EMF)$ of the battery. What is the ratio of the energy stored in the capacitor to the work done by the battery?

$A$ fully charged capacitor with capacitance $C$ is discharged through a small resistance coil embedded in a thermally insulated block of mass $m$ and specific heat $s$. If the temperature of the block increases by $\Delta T$,then the potential difference across the capacitor is:

What is the total energy of the given system in $joules$?