Now what if the sphere were made of glass (an insulator)? Although there aren’t
free electrons that can move to the near side of the sphere, the atoms that make up
the sphere will become polarized. That is, their electrons will feel a tug toward Q,
causing the atoms to develop a partial negative charge pointing toward Q (and a
partial positive charge pointing away from Q). The effect isn’t as dramatic as the
mass movement of free electrons in the case of a metal sphere, but the polarization
is still enough to cause an electrical attraction between the sphere and Q. For
example, if you comb your hair, the comb will pick up extra electrons, making it
negatively charged. If you place this electric field source near little bits of paper,
the paper will become polarized and be attracted to the comb.
Dipole-induced forces are caused by a shifting of the electron cloud of a neutral