Walker, Halliday & Resnick — Electric Fields: Problem 8

Figure 22-24 shows an uneven arrangement of electrons (e) and protons (p) on a circular arc of radius \( r = 2.50 \text{ cm} \), with angles \( \theta_1 = 30.0^\circ \), \( \theta_2 = 50.0^\circ \), \( \theta_3 = 30.0^\circ \), and \( \theta_4 = 20.0^\circ \). What are the (a) magnitude and (b) direction (relative to the positive direction of the x axis) of the net electric field produced at the center of the arc?