Question

Consider two electric dipoles in empty space. Each dipole has zero net charge. Does an electric force exist between the dipoles; that is, can two objects with zero net charge exert electric forces on each other? If so, is the force one of attraction or of repulsion?

Answer 1

Both dipoles consist of two poles of equal and opposite charges (as net charge is zero). These poles of a dipole exert force on each pole of other dipole. Net force on a dipole is sum of forces acting on each of it's pole due to each of the pole of other dipole. Force acting on each pole of a dipole from poles of other dipole are not equal, due to some distance between poles of a dipole, this net force is not zero. Hence electric force exists between two dipoles.
This force may be attractive or repulsive. Nature of force depends upon orientation of two dipoles. For example if similar charges of two dipoles, face each other, force is repulsive. If opposite charges of two dipoles face each other force is attractive.