NON POLAR DIELECTRICS:Are made of non-polar molecules.The center of mass of positive charges coincides with the center of mass of the negative charges, in the molecule.In its normal state (i.e., in the absence of any external force, esp electric field), each molecule has zero dipoles andhas a symmetric shape.POLAR DIELECTRICS:Are made of polar molecules.The center of mass of positive charges does not coincide with the center of mass of the negative charges, in the molecule.In its normal state (i.e., in the absence of any external force, esp electric field), each molecule has some intrinsic permanent dipole andhas an asymmetric shape.The dielectric constant is the ratio of the permittivity of a substance to the permittivity of free space. It is an expression of the extent to which a material concentrates electric flux, and is the electrical equivalent of relative magnetic permeability.