Write a relation for polarisation of a dielectric material in the presence of an external electric field .

Definition: When the dielectric material is exposed to external electric field, the dipole moment s formed in the material. The charge distribution changes inside the material as positive charge accommodates in the direction of the field and negative charge aligns in opposite direction of the external field applied. This phenomenon is called polarization.

Relation between polarisation, P of dielectric material in the presence of external electric field, E is given by P = χε₀.E Here χ is the susceptibility of medium. ε₀ is the permittivity of medium {free space} and E is the electric field intensity.