Internal energy change via heat and electric displacement change

Internal energy change of the system with a dielectric medium can be expressed using the infinitesimal heat flowing in or out of the system 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 31.2 on p. 122 of “General Course of Physics” (Obschiy kurs fiziki), vol. 3 by Sivukhin D.V. (1979).

internal_energy_density_change

Infinitesimal change in internal_energy per unit volume.

Symbol:

dU

Latex:

\(dU\)

Dimension:

energy/volume

heat_density

Small amount of heat added to or taken from the system per unit volume.

Symbol:

delta(Q)

Latex:

\(\delta Q\)

Dimension:

energy/volume

electric_field_strength

electric_field_strength in the medium.

Symbol:

E

Latex:

\(E\)

Dimension:

voltage/length

electric_displacement_change

Infinitesimal change in electric_displacement.

Symbol:

dD

Latex:

\(dD\)

Dimension:

charge/area

law

dU = delta(Q) + E * dD

Latex:

\[dU = \delta Q + E dD\]