The shows two parallel equipotential surfaces A and B at same potential kept at a distance ; apart from each other. A point charge -q is taken from surface A to B, the amount of net work done W will be :

• A

  $-\frac{1}{4{\mathrm{\pi \epsilon }}_0}\frac{\mathrm{q}}{\mathrm{r}}$

• B

  $\frac{1}{4{\mathrm{\pi \epsilon }}_0}\frac{\mathrm{q}}{{\mathrm{r}}^2}$

• C

  $-\frac{1}{4{\mathrm{\pi \epsilon }}_0}\frac{\mathrm{q}}{{\mathrm{r}}^3}$

• D

  Zero