Example 23.9 derives the exact expression for the electric field at a point on the axis of a uniformly charged disk. Consider a disk, of radius R = 3.00 cm, having a uniformly distributed charge of + 5.20 μC.
(a) Using the result of Example 23.9, compute the electric field at a point on the axis and 3.00 mm from the center. What If? Compare this answer with the field computed from the near-field approximation E = 2/2) 0.
(b) Using the result of Example 23.9, compute the electric field at a point on the axis and
30.0 cm from the center of the disk. What If? Compare this with the electric field obtained by treating the disk as a +5.20-μC point charge at a distance of 30.0 cm.