Particles in the @S06187@ of a phase are subjected to orienting forces as a result of the anisotropic force field. Polar molecules (e.g. permanent dipoles) may thus be preferentially oriented in the @S06187@, while polarizable molecules may be polarized (induced dipoles). The array of oriented polar and/or polarized molecules is called the surface dipole layer with which an @E01935@ drop is associated, called the surface potential of the phase.