the parallel plates in a capacitorm with a plate area of $6\mathrm{.}70$ cm$62$ and an air$-$filled separation of $4\mathrm{.}30$ mm are charged by a $7\mathrm{.}60$ V battery. They are then disconnected from the battery and pulled apart $($without discharge$)$ to a separation of $7\mathrm{.}20$mm$.$ Neglecting fringing