ABSTRACT
Polarization is the displacement of charges when we put a dielectric in an electric field. Under the electric field,
E the molecules or units of cells in the dielectric are electrically polarized, and a macroscopic polarization P emerges, as shown in Fig. 5.1. Quite often polarization
is parallel to the applied electric field and can be pointed in the same direction. A polarized dielectric has polarized charges on its
both ends. Between polarization P and electric field
E , we get the
following relation: P E= ce (5.1) where ce represents the electric susceptibility of the medium and has the same dimension as the dielectric constant. The macroscopic polarization P is related to the microscopic electric dipole moment p through the following relation: P N p= (5.2) where N is the number of atoms within a unit volume.
