Two particles have charges Q and −Q (equal magnitude and opposite sign). For a net force of zero to be exerted on a third charge it must be placed:
A. midway between Q and −Q
B. on the perpendicular bisector of the line joining Q and −Q, but not on that line itself
C. on the line joining Q and −Q, to the side of Q opposite −Q
D. on the line joining Q and −Q, to the side of −Q opposite Q
E. at none of these places (there is no place)
