Relative permittivity

Relative permittivity is the ratio of a material’s permittivity to the permittivity of vacuum. It describes how the material responds electrically to an applied field.

Electric susceptibility: A measure of how strongly a material polarizes in response to an electric field. For a linear isotropic dielectric, susceptibility determines relative permittivity through εᵣ = 1 + χₑ.
Permittivity: A material property relating electric displacement to electric field. Relative permittivity is defined by comparing this property with its vacuum value.
Dielectric: An electrical insulator that becomes polarized in an applied electric field. Relative permittivity quantifies a dielectric’s field response compared with vacuum.
Magnetic permeability: A material property relating magnetic induction to magnetic field strength. It describes magnetic response, whereas relative permittivity describes electric response.
Polarization density: Electric dipole moment per unit volume in a material. Bound charges shift or orient under an applied field, producing the polarization that affects permittivity.
Vacuum permittivity: The physical constant that sets the electric-field scale in vacuum. It is the denominator in the definition of relative permittivity.
Capacitor: An electrical component that stores energy in an electric field between conductors. The dielectric’s relative permittivity helps determine a capacitor’s capacitance.
Refractive index: A measure of how much light slows and bends in a medium. For transparent, nonmagnetic materials at optical frequencies, refractive index is approximately the square root of relative permittivity.
Dielectric relaxation: The delayed response of a material’s polarization to a changing electric field. Relaxation makes permittivity depend on the field’s frequency.
Electric displacement field: A field describing free charge and material polarization in electromagnetism. Its relation to the electric field includes permittivity.

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