Question

Two charged particles are 8cm apart.They are moved until the force between them triples.How far apart are they now?

Answer 1

Force$(F)$ is inversely proportional to $r^2$

So, $\frac{F_1}{F_2}=\frac{r_2^2}{r_1^2}$

As $F_2=3F_1$

Hence, $r_2=\frac{8}{\sqrt3}=4.6188cm$