Physics - Elecrostatics Question with Solution | TestHub

The electric potential for a point charge is given by 

$V=\frac{Q}{4\pi {\epsilon }_{0}r}$

The data given is 

$$\begin{gathered} V=50 \mathrm{V} \\ \mathrm{Q}=5\times {10}^{-9} \mathrm{C} \end{gathered}$$

So, the distance of the point is 

 $r=\frac{1}{4\pi {\epsilon }_0}\frac{Q}{V}$
$\Rightarrow r=9\times {10}^9\times \frac{5\times {10}^{-9}}{50}$
$\Rightarrow r=0.9 \mathrm{m}=90 \mathrm{cm}$