ABSTRACT
Dielectric materials possess relatively few free charge carriers. Most of the charge carriers are bound and cannot participate in conduction. However, these bound charges can be displaced by applying an external electric field. In such cases, the atom or molecule forms an electric dipole that maintains an electric field. Consequently, each volume element of the material behaves as an electric dipole. The dipole field tends to oppose the applied field. Dielectric materials that exhibit nonzero distribution of such bound charge separations are said to be
polarized
. The volume density of those electric dipoles is described by the volume density of polarization,
P
. When a material is linear and isotropic in nature, the polarization density is related to applied electric field intensity,
, as follows:
(10.1)
where
e
(= 8.854
¥
farad per meter) is the permittivity of free-space and
c
is called the electric susceptibility of the material.
