Question

at point P, which is on the central axis of the circle at distance z from the centre ?

• A. $0$
• B. $\frac{-10Q}{4\pi {\epsilon }_0\sqrt{R^2+Z^2}}$
• C. $\frac{-2Q}{4\pi {\epsilon }_0\sqrt{R^2+Z^2}}$
• D. $\frac{-5Q}{4\pi {\epsilon }_0\sqrt{R^2+Z^2}}$

Answer 1

The correct option is D $\frac{-5Q}{4\pi {\epsilon }_0\sqrt{R^2+Z^2}}$

Point P is equidistant from all the points on the circle.
Potential at P $=\frac{1}{4\pi ϵ}\frac{-6Q+Q}{\sqrt{R^2+Z^2}}=\frac{1}{4\pi ϵ}\frac{-5Q}{\sqrt{R^2+Z^2}}$