At the atomic scale, a molecule may have a permenant dipole moment if the electronic charge distribution is displaced with respect to the nuclear charge distribution. Molecules such as HF, OH, and H₂O are examples of this. A fluctuating dipole may be formed on a non-dipolar atom or molecule due to the time dependent relative movement between the centers of positive and negative charge. The electron distribution within the molecule moves with respect to the positive nucleus of greater mass. An applied electric field may also generate such a charge displacement, creating an electric dipole moment on the atom.

The electric field components associated with a dipole have the form: 
E_r = 2p cosq/r³, and E_q = p sinq/r³ , where p is the dipole moment and q the angle between the dipole axis and the and the position vector, r. This field will interact with another dipole giving rise to a force between the two dipoles.