Question

Displacement relation with electric field and polarization

Answer 1

Answer:

The electric displacement field is a vector field that accounts for the effects of free and bound charge within materials.The electric displacement field is related to the electric field and the polarization density

Answer 2

Explanation:

Let us derive the relation between polarization vector (P), displacement (D) and electric field (E):

In the last article of polarization, we have discussed about the effect on dielectric placed in an external electric field E0 and there will be electric field due to polarized charges, this field is called electric field due to polarization (Ep). (You can see the figure in that article).

Rewrite equation (1) of that article, that is:

E = E0 – Ep (1)

Polarization vector, P = P is equal to the bound charge per unit area or equal to the surface density of bound charges (because surface charge density is charge per unit area),

Thus P = qb/A = σp (2)

Where qb is bound charge and σp is surface density of bound charges.

P is also defined as the electric dipole moment of material per unit volume.

P = np

where n is number of molecules per unit volume.