Explain the polarization of a polar molecule in a uniform electric field.

(N/A) In the absence of an external electric field,the permanent dipole moments of polar molecules are oriented randomly due to thermal agitation. Consequently,the net dipole moment of the entire material is zero.
When an external electric field is applied,these individual dipole moments tend to align themselves with the direction of the field. When summed over all the molecules,this results in a net dipole moment in the direction of the external field,meaning the dielectric becomes polarized,as shown in the figure.
The extent of this polarization depends on the competition between two mutually opposite factors: the dipole potential energy in the external field,which tends to align the dipoles with the field,and thermal energy,which tends to disturb this alignment.
Generally,the alignment effect is significant for polar molecules.