Electric susceptibility

In electricity (electromagnetism), the electric susceptibility ${\displaystyle \chi _{\text{e}}}$ (latin: susceptibilis “receptive”) is a dimensionless proportionality constant that indicates the degree of polarization of a dielectric material in response to an applied electric field. The greater the electric susceptibility, the greater the ability of a material to polarize in response to the field, and thereby reduce the total electric field inside the material (and store energy). It is in this way that the electric susceptibility influences the electric permittivity of the material and thus influences many other phenomena in that medium, from the capacitance of capacitors to the speed of light.

Electric susceptibility is defined as the constant of proportionality (which may be a tensor) relating an electric field E to the induced dielectric polarization density P such that:

where

The susceptibility is related to its relative permittivity ${\displaystyle \varepsilon _{\textrm {r}}}$ by:

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