Q 12-02-025NEETJEE MainMedium
A hollow metal sphere of radius $10$ cm carries a charge that makes its surface potential $80$ V. The potential at its centre and at $20$ cm from its centre are
Answer: (B) $80$ V and $40$ V
Concept. Inside: surface value; outside: $V \propto \dfrac1r$.
Step 1. Centre. $80$ V.
Step 2. At 20 cm. $40$ V.
Answer. $80$ V and $40$ V (Option B).
Solution by Sreeraj P, M.Sc Physics