Two charges are located on the x axis: q1 = +6.8 μC at x1 = +4.7 cm, and q2 = +6.8 μC at x2 = −4.7 cm. Two other charges are located on the y axis: q3 = +3.6 μC at y3 = +4.9 cm, and q4 = −9.2 μC at y4 = +7.0 cm. Find (a) the magnitude and (b) the direction of the net electric field at the origin. (a) Number Units