# Dielectric Material Motivation: Understand the difference between [[Permittivity]] and [[Resistivity]]. A dielectric, or dielectric materials are electric insulators (poor conductors) that can be polarized by an applied electric field, rather than transfer charges. A good dielectric material is one that is easily polarized. The dielectric constant of a material, also known as the [[Permittivity |relative permittivity]] of a material, represents the ability of material to store electric energy in the presence of an electric field. The dielectric constant of a vacuum, $\varepsilon_0 = 8.854 \times 10^{-12} F/m$.