ABSTRACT
When a material consists of molecules with permanent electric dipoles (see Topic H5), the electrostatic force between molecules changes their potential energy. The energy, U(r), of the electrostatic interaction between two parallel dipoles with dipole moments µ1 and µ2, a distance r apart, is given by:
where θ is the angle between the dipole axes and the vector linking the centers of the two dipoles. This potential is a maximum if θ=0°, when the positive pole of one dipole experiences only the negative pole of the second. The potential is zero if θ=90°, as both negative and positive poles of one dipole are experienced equally, and so cancel out, at the second dipole.
