A capacitor $C$ is charged to a potential difference $V$ and battery is disconnected. Now if the capacitor plates are brought close slowly by some distance :

If the charge on a capacitor is increased by $2$ coulomb, the energy stored in it increases by $21\%$. The original charge on the capacitor is....$C$

A parallel plate capacitor is connected to a battery. The plates are pulled apart with a uniform speed. If $x$ is the separation between the plates, the time rate of change of electrostatic energy of capacitor is proportional to

A $16\  \Omega$ wire is bend to form a square loop. A $9 \mathrm{~V}$ battery with internal resistance $1\  \Omega$ is connected across one of its sides. If a $4\  \mu \mathrm{F}$ capacitor is connected across one of its diagonals, the energy stored by the capacitor will be $\frac{x}{2} \ \mu \mathrm{J}$. where $x=$________.

A $6\,\mu F$ capacitor is charged from $10\;volts$ to $20\;volts$. Increase in energy will be

capacitor is used to store $24\, watt\, hour$ of energy at $1200\, volt$. What should be the capacitance of the capacitor