Dielectric

It is an electrical insulator that can be polarized by an electric field. Actually all insulators can be polarized by an electric field. Not all insulators are good dielectrics.

Dielectrics are important for explaining various phenomena in electronics, optics, solid state physics and cell biophysics.

The polarizability of a dielectric is called it's Permittivity. The relative polarizability of a material with respect to vacuum is called it's dielectric constant, or relative permittivity.

Dielectric constant

• For metals, it is 1, same as vacuum
• For all other insulators, the value is greater than 1.