Two identical conducting spheres $P$ and $S$ with charge $Q$ on each, repel each other with a force $16 \mathrm{~N}$. A third identical uncharged conducting sphere $R$ is successively brought in contact with the two spheres. The new force of repulsion between $\mathrm{P}$ and $\mathrm{S}$ is :

Question

Aicharya · Accepted Answer

$\begin{aligned} & F_{P S} \propto Q^2 \\ & F_{P S}=16 \mathrm{~N} \end{aligned}$
Now If $\mathrm{P} ~\&~ \mathrm{R}$ are brought in contact then

Now If $S \& R$ are brought in contact then

New force between $P ~\&~ S$ is : $\begin{aligned} & \mathrm{F}_{\mathrm{PS}} \propto \frac{\mathrm{Q}}{2} \times \frac{3 \mathrm{Q}}{4} \\ & \mathrm{~F}_{\mathrm{PS}} \propto \frac{3 \mathrm{Q}^2}{8}=\frac{3}{8} \times 16=6 \mathrm{~N} \end{aligned}$

Two identical conducting spheres $P$ and $S$ with charge $Q$ on each, repel each other with a force $16…

Solution