Question 369: Electrostats & Capacitance

Question

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 $$\mathrm{R}$$ is successively brought in contact with the two spheres. The new force of repulsion between $$\mathrm{P}$$ and $$\mathrm{S}$$ is :

Accepted Answer

$$\begin{aligned}
& F_1=\frac{K Q^2}{r^2}=16 \mathrm{~N} \
& F_2=\frac{K\left(\frac{Q}{2}ight)\left(\frac{3}{4}ight)}{r^2}=\frac{3}{8} 	imes 16=6 \mathrm{~N}
\end{aligned}$$
Final charges on spheres are $$\frac{Q}{2}$$ and $$\frac{3 Q}{4}$$.

Answer

1 N

Answer

6 N

Answer

12 N

Answer

4 N

Electrostats & Capacitance

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

Choose the correct answer: