Figure 18.65 An electric dipole (with +2q and –2q as the two charges) is shown in the figure below. A third charge, −q is placed equidistant from the dipole charges. What will be the direction of the net force on the third charge?
This is College Physics Answers with Shaun Dychko. This distribution of charges is going to exert a force on this bottom charge negative q, this charge will be attracted to the plus 2q charge because they are oppositely charged and there's going to be an equal magnitude repulsion from the negative 2q charge; equal magnitudes since this magnitude of this charge is the same as the magnitude of this charge only their signs are different and so the direction of the force will be different, it's gonna be attracted here on the one hand but repelled from the negative 2q charge. The resultant of these two forces will be horizontal and so this is the direction of the net force on the charge and the answer is (a).