Question

What would happen to the electrostatic force between a pair of charged particles if both charges were tripled and the distance between them were also tripled?

• A. It would decrease by a factor of $4$
• B. It would decrease by a factor of $2$
• C. It would remain unchanged
• D. It would increase by a factor of $2$
• E. It would increase by a factor of $4$

Answer 1

Answer: (C)

It would remain unchanged

The electric force between two charges $q_1$ and $q_2$ is $F=\frac{k{q}_1{q}_2}{r^2}$ where r be the distance between them.

Now, $F^{\prime }=\frac{k{q}_1^{\prime }{q}_2^{\prime }}{r^{\prime 2}}=\frac{k\left(3q_1\right)\left(3q_2\right)}{(3r{)}^2}=\frac{k{q}_1{q}_2}{r^2}=F$