The variation of potential with distance $R$ from a point is as shown in figure. The electric field

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The variation of potential with distance $R$ from a point is as shown in figure. The electric field at $R=5 \mathrm{~m}$ is\

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Field $=-$ ve gradient of potential $$ \mathrm{E}=-\frac{\Delta \mathrm{V}}{\Delta \mathrm{r}} $$ Case I: $\mathrm{r}=5 \mathrm{~m} \Delta \mathrm{r}=6-4=2 \mathrm{~m}$\ $\Delta \mathrm{V}=0-5=-5$ volt\ $	herefore \mathrm{E}=-\frac{(-5)}{2}=2.5 \mathrm{~V} / \mathrm{m}$\ Case II : $\mathrm{r}=1 \mathrm{~m} \Delta \mathrm{r}=2-0=2 \mathrm{~m}$\ $\Delta \mathrm{V}=5-0=5 \mathrm{~V}$\ $E=-\left(\frac{5}{2}ight) V / m$ Case III: $\mathrm{r}=3 \mathrm{~m} \Delta \mathrm{r}=4-2=2 \mathrm{~m}$\ $\Delta \mathrm{V}=5-5=0 \mathrm{~V} \quad 	herefore \mathrm{E}=0$\