Answer
The correct answer is:
(a) $\frac{F}{2}$
Work Step by Step
We can write an expression for the original force:
$F = \frac{k~q_1~q_2}{r^2}$
We can write an expression for the new force:
$F' = \frac{k~(2q_1)~q_2}{(2r)^2} = \frac{1}{2}\times \frac{k~q_1~q_2}{r^2} = \frac{F}{2}$
The correct answer is:
(a) $\frac{F}{2}$
