The four types of polarization which occur in dielectrics are:
(I) Electronic polarization,
(II) Ionic polarization,
(III) Orientation or dipole polarization,
(IV) Space charge or interfacial polarization
Let us discuss them one by one:
(I) Electronic polarization. Electronic polarization occurs due to displacement of the centre of the negatively charged electron cloud relative to the positive nucleus of an atom by the electric field.
Example. Monoatomic gases exhibit only electronic polarization.
The shifting of electron cloud results in dipole moment and dipole moment p is defined as the product of the charge and shift distance,
that is p = qd
Dipole moment p is also directly proportional to electric field strength, E thus p is proportional to E
Or p = αeE (1)
where αe is constant of proportionality known as electronic polarizability constant.
Electronic polarization Pe is given as
where n is number of molecules per unit volume.
By putting value of p from equation (1) in above equation, we get
Pe =n αeE
This polarization is independent of temperature.
Note: In next article, I will discuss ionic polarization. This article is referred from my authored book. In case of any problem in this article or any other physics article, kindly post in the comment section.