A charged rod will attract an uncharged pith ball since it induces a dipole moment in the uncharged pith ball, which now has a dipole moment, is attracted in the inhomogeneous field surrounding the ch...A charged rod will attract an uncharged pith ball since it induces a dipole moment in the uncharged pith ball, which now has a dipole moment, is attracted in the inhomogeneous field surrounding the charged rod. How may a dipole moment be induced in an uncharged body? Well, if the uncharged body is metallic, then once placed in an electric field, the free electrons are attracted to one end of the metal, leaving an excess of positive charge at the other end; this induces a dipole moment.
