Surface charge distributions. Problem 2.22 of the Wentworth textbook (25 points). Consider a circular disk in the x-y plane of the radius 5cm. suppose the charge density is a function of radius such that ps 12p nC/cm², when the radius is measured in cm. = a. Find the electric field intensity at a point 20 cm above the origin on the z axis. b. Find the electric potential at the same point as in part (a). Hint: you may assume that the disk is centered at the origin.