The electric field along the axis of a uniformly charged disk of radius R and total charge Q was calculated in Example 23.3. Show that the electric field at distances x that are large compared with R approaches that of a particle with charge . Suggestion: First show that and use the binomial expansion , when .
Example 23.3. A disk of radius R has a uniform surface charge density . Calculate the electric field at a point P that lies along the central perpendicular axis of the disk and a distance x from the center of the disk.
