Its real part gives the Fresnel reflection coefficients, and it relates the displacement field to the electric field.
When dispersion takes place in a traveling wave, this quantity must satisfy the Kronig-Kramers relations. The imaginary part of this quantity yields the radio absorption coefficient, and this quantity can also be calculated from the Clausius-Mossotti equation. For a plasma, it is given by one minus the plasma frequency over the wave frequency, and for continuous macroscopic bodies this quantity is given by one plus the electric succeptibility. Its real part gives the Fresnel reflection coefficients, and it relates the displacement field to the electric field. Also called the relative permeability, for ten points, identify this constant whose namesake materials are often inserted between the plates of capacitors.
When dispersion takes place in a traveling wave, this quantity must satisfy the Kronig-Kramers relations.
dielectric constant