One thousand spherical oil droplets, each of radius r and each carrying a charge q, coalesce to form a single spherical drop. If v is the electrical potential of each droplet and V that of the bigger drop, then

If R is the radius of the big drop, we have

                 $\frac{4{\mathrm{\pi R}}^3}{3}=1000\times \frac{4\pi r^3}{3}$

which gives R = 10 r. The electrical potential of each droplet is 

                  $v=\frac{q}{4{\mathrm{\pi \epsilon }}_0\mathrm{r}}$

and that of the big drop is 

            $V=\frac{1000q}{4{\mathrm{\pi \epsilon }}_0\mathrm{R}}$

$\therefore \frac{V}{v}=\frac{1000r}{R}=100$