A point charge of +Q is placed at the center of
;k yjjd42*if5 nsm6gy a square, and a second point charge of -Q 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
*i46yn s;d25gj mjyfk-Q is placed at the lower-left corner?