# 2.2.7: Potential on the Axis of a Charged Disc

The field on the axis of a charged disc is given in section 1.6.5. The reader is invited to show that the potential on the axis of the disc is

\[V=\frac{2Q}{4\pi\epsilon_0 a^2}[(a^2+x^2)^{1/2}-x].\tag{2.2.9}\]