Electric displacement field

The electric displacement field is a vector field defined by D = ε₀E + P, combining the electric field with a material’s polarization. Its divergence is tied to free charge in macroscopic electromagnetism.

Gauss's law: A law relating electric flux through a closed surface to the charge enclosed. For D, its macroscopic form makes the enclosed free charge determine net flux.
Electric field: A vector field that describes the electric force per unit positive test charge. D combines the macroscopic electric field E with the polarization of matter.
Electric flux density: A vector quantity describing electric flux per unit area, commonly denoted D in macroscopic electromagnetism. This is a common alternate name for the electric displacement field, though terminology varies.
Capacitance: The ratio of stored electric charge to potential difference for a conductor system. In dielectric-filled capacitors, D helps relate electrode free charge to the field in the material.
Electric polarization: The electric dipole moment per unit volume in a material, describing its response to an electric field. Polarization supplies the material contribution P in D = ε₀E + P.
Vacuum permittivity: The physical constant ε₀ that sets the scale of electromagnetic interactions in vacuum. It weights E in the defining expression D = ε₀E + P.
Microscopic electric field: The electric field at atomic scales, including contributions from individual charges and dipoles. D is a macroscopic field and does not resolve the rapidly varying microscopic field.
Dielectric: An electrical insulator that polarizes in response to an applied electric field. D is especially useful for describing fields and free charge inside dielectric materials.
Electric susceptibility: A dimensionless measure of how strongly a material polarizes in response to an electric field. In a linear dielectric, susceptibility links P to E and helps determine D.
Bound charge: Electric charge associated with the polarization of atoms and molecules in matter. Polarization charge is separated from free charge in the macroscopic equations for D.

Linked from 12 pages