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

If the charge on the capacitor is increased by $3 \ C$,the energy stored in it increases by $21 \%$. The original charge on the capacitor is (in $C$)

$A$ parallel plate capacitor has plate area $A$ and separation $d$. It is charged to a potential difference $V_0$. The charging battery is disconnected and the plates are pulled apart to three times the initial separation. The work required to separate the plates is

$A$ parallel plate capacitor carries a charge $q$. The distance between the plates is doubled by the application of a force. The work done by the force is

If the charge on the capacitor is increased by $3 \ C$,the energy stored in it increases by $44 \%$. The original charge on the capacitor is (in $C$)

If the potential difference across a capacitor is increased from $5 \,V$ to $15 \,V$, then the ratio of final energy to initial energy stored in the capacitor is