Please.:
(a) What is the value of electric field intensity at any point on an equipotential surface ?

$$\begin{gathered} \left(\mathrm{i}\right) \mathrm{Zero}. \left(\mathrm{ii}\right) \frac{1}{4{\mathrm{\pi \epsilon }}_{\mathrm{o}}}\frac{\mathrm{Q}}{\mathrm{r}}. \\ \left(\mathrm{iii}\right) \frac{1}{4{\mathrm{\pi \epsilon }}_{\mathrm{o}}}\frac{\mathrm{Q}}{{\mathrm{r}}^2}. \left(\mathrm{iv}\right) \mathrm{None}. \end{gathered}$$