Gibbs energy of dielectrics
===========================

Gibbs energy of the system with a dielectric medium can be expressed using
the Helmholtz free energy and the electric displacement and field strength.

**Conditions:**

#. The dielectric is isotropic whether or not the electric field is present.
#. The medium is homogeneous.
#. The volume change of the medium is insignificant.

**Links:**

#. Formula 31.4 on p. 122 of "General Course of Physics" (Obschiy kurs fiziki), vol. 3 by Sivukhin D.V. (1979).

.. py:currentmodule:: symplyphysics.laws.thermodynamics.dielectrics.gibbs_energy_formula

.. py:data:: gibbs_energy_density

    :attr:`~symplyphysics.symbols.thermodynamics.gibbs_energy` of the system per unit :attr:`~symplyphysics.symbols.classical_mechanics.volume`.

Symbol:
    :code:`G`

Latex:
    :math:`G`

Dimension:
    :code:`energy/volume`


.. py:data:: free_energy_density

    :attr:`~symplyphysics.symbols.thermodynamics.helmholtz_free_energy` of the system per units :attr:`~symplyphysics.symbols.classical_mechanics.volume`.

Symbol:
    :code:`F`

Latex:
    :math:`F`

Dimension:
    :code:`energy/volume`


.. 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:: electric_displacement

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

Symbol:
    :code:`D`

Latex:
    :math:`D`

Dimension:
    :code:`charge/area`


.. py:data:: law

    :code:`G = F - E * D`


    Latex:
        .. math::
            G = F - E D