The circular disk of radius a shown in Fig. 4-7 (P4.28) has

The circular disk of radius a shown in Fig. 4-7 (P4.28) has uniform charge density ?s across its surface.
(a) Obtain an expression for the electric potential V at a point P (0, 0, z) on the z-axis.
(b) Use your result to find E and then evaluate it for z = h. Compare your final expression with Eq. (4.24), which was obtained on the basis of Coulomb’s law.