A point charge of +Q is placed at the
d .-(+ije9 ijr tvys9;4v,tzm ( cwtuocenter of a square, and a second point charge of -Q
v(r tjm i9(;4j,y.+ e-dituwotczs v9 is placed at the upper-left corner. It is observed that an electrostatic force of 2.0 N acts on the positive charge at the center. What is the magnitude of the force that acts on the center charge if a third charge of -Q is placed at the lower-left corner?