Electric displacement is permittivity times electric field
==========================================================

In a linear, homogeneous, isotropic dielectric the electric displacement is linearly
proportional to the electric field strength, with the constant of proprortionality
being the permittivity of the medium.

**Notes:**

#. If the medium is anisotropic, the relation between electric displacement and
   electric field is similar, but permittivity is now a tensor and not a scalar.

#. In a nonhomogeneous medium, permittivity is a function of position inside the medium.

#. In a nonlinear medium, permittivity is a function of the electric field and has a
   time-dependent response.

**Conditions:**

#. The medium is linear, homogeneous, and isotropic.

**Links:**

#. `Wikipedia <https://en.wikipedia.org/wiki/Electric_displacement_field#Definition>`__.

.. py:currentmodule:: symplyphysics.laws.electricity.electric_displacement_is_permittivity_times_electric_field

.. py:data:: electric_displacement

    :attr:`~symplyphysics.symbols.electrodynamics.electric_displacement` in the medium.

Symbol:
    :code:`D`

Latex:
    :math:`D`

Dimension:
    :code:`charge/area`


.. py:data:: absolute_permittivity

    :attr:`~symplyphysics.symbols.electrodynamics.absolute_permittivity` of the medium.

Symbol:
    :code:`epsilon`

Latex:
    :math:`\varepsilon`

Dimension:
    :code:`capacitance/length`


.. py:data:: electric_field_strength

    :attr:`~symplyphysics.symbols.electrodynamics.electric_field_strength` in the medium.

Symbol:
    :code:`E`

Latex:
    :math:`E`

Dimension:
    :code:`voltage/length`


.. py:data:: law

    :code:`D = epsilon * E`


    Latex:
        .. math::
            D = \varepsilon E