Free energy change via temperature change and electric displacement change

The infinitesimal change in (Helmholtz) free energy of a system with a dielectric medium can be expressed using the change in temperature and the change in electric displacement.

Conditions:

1. The dielectric is isotropic whether or not the electric field is present.

2. The medium is homogeneous.

3. The volume change of the medium is insignificant.

Links:

1. Formula 31.7 on p. 122 of “General Course of Physics” (Obschiy kurs fiziki), vol. 3 by Sivukhin D.V. (1979).

free_energy_density_change

Infinitesimal change in helmholtz_free_energy of the system per unit volume.

Symbol:

dH

Latex:

\(dH\)

Dimension:

energy/volume

entropy_density

entropy of the system per unit volume.

Symbol:

S

Latex:

\(S\)

Dimension:

energy/(temperature*volume)

temperature_change

Infinitesimal change in temperature of the system.

Symbol:

dT

Latex:

\(dT\)

Dimension:

temperature

electric_field_strength

electric_field_strength.

Symbol:

E

Latex:

\(E\)

Dimension:

voltage/length

electric_displacement_change

Infinitesimal change in electric_displacement of the system.

Symbol:

dD

Latex:

\(dD\)

Dimension:

charge/area

law

dH = -S * dT + E * dD

Latex:

\[dH = - S dT + E dD\]