2.2E: Potential on the Axis of a Charged Ring
( \newcommand{\kernel}{\mathrm{null}\,}\)
The field on the axis of a charged ring is given in section 1.6.4. The reader is invited to show that the potential on the axis of the ring is
V=Q4πϵ0(a2+x2)1/2.
You can do this either by integrating the expression for the field or just by thinking about it for a few seconds and realizing that potential is a scalar quantity.