Q 12-02-088JEE MainJEE Main 2023 (24 Jan, Shift 2)Medium
The electric potential at the centre of two concentric half rings of radii $R_1$ and $R_2$, having same linear charge density $\lambda$, is
Answer: (B) $\dfrac{\lambda}{2\epsilon_0}$
All the charge of a half ring of radius $R$ ($q=\lambda\pi R$) is at distance $R$ from $O$:
$$V=\frac{\lambda\pi R}{4\pi\epsilon_0R}=\frac{\lambda}{4\epsilon_0}$$
independent of $R$. Two rings: $V=\dfrac{\lambda}{2\epsilon_0}$.
Solution by Sreeraj P, M.Sc Physics