Example 5 The figure shows an uneven arrangement of electrons (e) and protons (p) on a circular arc of radius r = 2.00 cm, with angles P 01 = 30.0, 02 = 50.0, 03 = 30.0, and 04 = 20.0. What are the (a) magnitude and (b) direction (relative to the positive P P direction of the x axis) of the net electric field produced at the center of the arc? e 21-1