Q 12-01-018NEETJEE MainMedium
A uniformly charged solid sphere of radius $R$ produces a field $E_0$ at its surface. The field at distance $\dfrac{R}{2}$ from the centre and at distance $2R$ from the centre are
Answer: (B) $\dfrac{E_0}{2}$ and $\dfrac{E_0}{4}$
Concept. For a uniformly charged solid sphere, $E \propto r$ inside and $E \propto \dfrac{1}{r^2}$ outside.
Step 1. At $\dfrac{R}{2}$. $E = \dfrac{E_0}{2}$.
Step 2. At $2R$. $E = \dfrac{E_0}{4}$.
Answer. $\dfrac{E_0}{2}$ and $\dfrac{E_0}{4}$ (Option B).
Solution by Sreeraj P, M.Sc Physics