Question

Two identical conducting balls have positive charges $q_1$ and $q_2$ respectively. The balls are brought together so that they touch and then put back in their original positions. The force between the balls may be

• A. Greater than before the balls touched
• B. Remain same as it was before the balls touched.
• C. Less than before the balls touched
• D. Zero

Answer 1

The correct option is A Greater than before the balls touched

Let separation between the charges be $r,$

$F_i\propto q_1{q}_2.....\left(1\right)$

After touching, new charges on each ball is $\frac{q_1+q_2}{2}$

$F_{new}\propto {\left(\frac{q_1+q_2}{2}\right)}^2.....\left(2\right)$

From (1) and (2)

As, ${\left(\frac{q_1+q_2}{2}\right)}^2>q_1{q}_2$

$\Rightarrow F_{new}>F_i$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(B\right)$ is the correct answer.