Question

Two electric charges q₁ and q₂ are initially separated by distance r_i . When the two charges are moved farther apart, the magnitude of the electric force reduces three times the initial. How many times the separation distance between them increases?

Answer 1

According to the Coulomb's law the electric force is proportional to the product of charges and proportional to $r^{-2}.$

$F = \dfrac{kq_1q_2}{r^2}.$

Therefore, if the force reduces three times the initial, then the distance increases as $\sqrt{3}\approx 1.73.$