Engineering physics

1. TYPES OF POLARIZATION
MADE BY
AAKASH TOMAR
ENG21DS0001

2. WHAT IS DIELECTRIC POLARIZATION
When an electric field is applied across a dielectric material then
the dielectric material becomes polarized . This mechanism is
called dielectric polarization.

3. TYPES OF POLARIZATION
There are four types of polarization
1. Electronic polarization
2. Ionic polarization
3. Orientational polarization
4. Space charge polarization

4. Electronic Polarization

5. Expression for Electronic Polarization

9. • Hence electronic polarizability is directly proportional to cube of the
radius of the atom

10. Ionic polarization

16. Orientational Polarization
When an electric field is applied on an dielectric material with
permanent dipole moment (μ), the applied field tries to orient the
dipole along its direction . The orientational polarization is given by
αo is orientation polarizability

17. • Thus the orientational polarizability is a temperature dependent term
and is inversely proportional to the absolute temperature of the
dielectric material.
• It is slow process compare to ionic and electronic polarization.
• All the molecular dipoles are oriented randomly when there is no
Electric field.
• In the presence of the electric field these dipoles orient themselves in
the direction of field as a result the net dipole moment becomes
enormous.

18. Space charge polarization
• When an electric field is applied to a bulk dielectric material the
charges in the material diffuse to a considerable distance with
response to the applied field .
• This is very slow process and contribution to the total polarization
from space charge polarization is neglizible .

19. Total Polarization
• Total Polarization is the sum of polarizations due to electronic ,ionic,
orientational and space charge polarizabilities.

20. THANK YOU