Permittivus

Permittivus is a hypothetical electromagnetic parameter used in theoretical and educational contexts to describe how a material permits electric displacement in response to an electric field, particularly in models that extend beyond the standard linear, isotropic permittivity.

In a generalized constitutive relation, the displacement D is related to the electric field E through D = Permittivus · E. Here Permittivus can be a scalar in isotropic media or a second-rank tensor in anisotropic media. In nonlinear or dispersive scenarios, Permittivus may depend on the field strength, frequency, temperature, or other state variables, and it can be complex-valued to reflect loss.

Permittivus is typically discussed as an alternative or pedagogical label to the conventional permittivity ε. In linear, homogeneous, and isotropic media, Permittivus would reduce to ε, while in more complex media it serves to highlight generalized responses that are not captured by a single constant permittivity. The concept helps frame discussions of nonlinearities, spatial dispersion, and frequency-dependent behavior without committing to a particular material model.

Historically, permittivus is not a standard term in mainstream electromagnetism or materials science. It appears mainly in classroom explanations, thought experiments, or speculative literature aimed at illustrating how generalized constitutive relations might behave in advanced materials such as nonlinear dielectrics or metamaterials.

See also permittivity, dielectric, nonlinear optics, anisotropy, constitutive relations, metamaterials.