Electric susceptibility is a dimensionless proportionality constant that indicates the degree of polarization of a dielectric material in response to an applied electric field. Here P = epsilon_0 * chi_e * E. Where epsilon_0 is the electric permittivity of free space (electric constant), P is the polarization density of the material chi_e is the electric susceptibility and E is the electric field.
\chi_{\text{e}} = \frac{{\mathbf P}}{\varepsilon_0{\mathbf E}}
Electric Susceptibility Unit