Two point charges are fixed on the y axis: a negative point charge q1 = -23 µC at y1 = +0.23 m and a positive point charge q2 at y2 = +0.33 m. A third point charge q = +7.8 µC is fixed at the origin. The net electrostatic force exerted on the charge q by the other two charges has a magnitude of 29 N and points in the +y direction. Determine the magnitude of q2.
F1 = k•(q•q1)/(0.23)^2 (points +y- direction)
F2 = k•(q•q2)/(0.33)^2 (points -y- direction)
F =29 N = F1 –F2
k=1/4πε(o) = 9•10^9 N•m^2•C^-2
posted by Elena