Two point charges $q_1$ and $q_2$ are ' $l$ ' distance apart. If one of the charges is doubled and the…
Two point charges $q_1$ and $q_2$ are ' $l$ ' distance apart. If one of the charges is doubled and the distance between them is halved, the magnitude of force becomes $n$ times, where $n$ is
$8$
$1$
$2$
$16$
Solution
The correct option is (A)
Concept: Functional dependence of Coulombic Force on charges $\left(q_1, q_2\right)$ separated with distance $l$ is given by
$F \propto \frac{q_1 q_2}{l^2}$
Therefore, if one of the charges is doubled and the distance between them is halved, the magnitude of new force
$F_{\text {new }} \propto\left\{\frac{2 q_1 q_2}{\left(\frac{l}{2}\right)^2}\right\}$
So, $F_{\text {new }}=8 F$.