A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system

The diagrams below show regions of equipotential.



A positive charge is moved from $A$ to $B$ in each diagram.

A parallel-plate capacitor of area $A$, plate separation $d$ and capacitance $C$ is filled with four dielectric materials having dielectric constants$k_1$, $k_2$, $k_3$ and $k_4$ as shown in the figure below. If a single dielectric material is to be used to have the same capacitance $C$ in this capacitor, then its dielectric constant $k$ is given by

A capacitor of $\mathrm{2 }\mathrm{\mu F}$ is charged as shown in the diagram. When the switch $\mathit{\text{S}}$ is turned to position $2$, the percentage of its stored energy dissipated is