The ‘absolute’ permittivity of a dielectric, being the ratio of the electric displacement to the electric field strength at the same point. Its value for free space is 8.854185 × 10−12 F/m. The real component of the complex relative permittivity is an important diagnostic parameter when considering the high- and low-frequency values for zero dielectric loss. It relates to grain size, packing variations, and density of the material. See also dielectric constant.