Q 12-01-131JEE MainJEE Main 2020 (6 Sep, Shift 2)Easy
Consider the force $F$ on a charge $q$ due to a uniformly charged spherical shell of radius $R$ carrying charge $Q$ distributed uniformly over it. Which one of the following statements is true for $F$, if $q$ is placed at distance $r$ from the centre of the shell?
Answer: (C) $F = \dfrac{1}{4\pi\varepsilon_0}\dfrac{Qq}{r^2}$ for $r > R$
Inside a uniformly charged shell the field is zero, so $F = 0$ for $r < R$.
Outside, the shell acts as a point charge at its centre, so $F = \dfrac{1}{4\pi\varepsilon_0}\dfrac{Qq}{r^2}$ for $r > R$.
Solution by Sreeraj P, M.Sc Physics