A small uncharged conducting sphere is placed in contact with an identical sphere but having $4 imes10^{-8}$ C charge and then removed to a distance such that the force of repulsion between them is $9 imes10^{-3}$ N. The distance between them is (Take $\frac1{4\pi\epsilon_0}$ as $9 imes10^9$ in SI units)

Question

A small uncharged conducting sphere is placed in contact with an identical sphere but having $4	imes10^{-8}$ C charge and then removed to a distance such that the force of repulsion between them is $9	imes10^{-3}$ N. The distance between them is (Take $\frac1{4\pi\epsilon_0}$ as $9	imes10^9$ in SI units)

Dr. Abubacker · Accepted Answer

[Solution by Dr. Abubacker] Each sphere gets $2	imes10^{-8}$ C. $F=\frac{kq^2}{r^2}\Rightarrow r^2=\frac{9	imes10^9	imes4	imes10^{-16}}{9	imes10^{-3}}=4	imes10^{-4}$, so $r=2	imes10^{-2}$ m $=2$ cm. Answer (2).

Explanation

Reviewed by Dr. Abubacker

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