Chapter 22, Problem 77P

Measurements of the potential at points on the axis of a charged disk are given in the two tables below, one for measurements made close to the disk and the other for measurements made far away. In both tables x is the coordinate measured along the disk axis with the origin at the disk center, and the zero of potential is taken at infinity, (a) For each set of data, determine a quantity that, when you plot potential against it. Should yield a straight line. Make your plots, establish a best-fit line, and determine its slope. Use your slopes to find (b) the total charge on the disk and (c) the disk radius. (Hint: Consult Example 22.7.)

Table 1

x(mm)	2.0	4.0	6.0	8.0	10.0
V(V)	900	876	843	820	797

Table 2

x(cm)	20	30	40	60	100
V(V)	165	118	80	58	30