A disk with radius R has uniform surface charge density (a) By regarding the disk as a

Question:

A disk with radius R has uniform surface charge density σ
(a) By regarding the disk as a series of thin concentric rings, calculate the electric potential V at a point on the disk's axis a distance x from the center of the disk. Assume that the potential is zero at infinity
(b) Calculate -∂v/∂x. Show that the result agrees with the expression for Ex calculated in Example 21.12 (Section 21.5).