Figure 1) shows four charges at the corners of a square of side L.

What magnitude and sign of charge *Q* will make the force on charge *q* zero?

The vertical forces acting on q are:

{eq}F_y = kq(\frac{4Q}{2L^2}\sin{45} – \frac{Q}{L^2}) \\ F_y = kq(\frac{1.414Q}{L^2}-\frac{Q}{L^2}) \\ F_y =…