Summary

Here, we saw that polarization is caused by the movement of electrons or ions or molecules from their equilibrium positions and is frequency dependent. This is because the mass of each entity is different and hence time scales are different. Basically, there are four polarization mechanisms: electronic, ionic, dipolar or orientation and interface and each of these mechanisms is characterized by different polarizability. The net polarizability of a solid will be sum of these four polarizabilities.

We also learnt that the local field inside a dielectric is not the same as the applied electric field. This field is a result of various microscopic and macroscopic fields inside the dielectric. This leads to derivation of Clausius-Mossotti equation which relates the microscopic dielectric properties to the macroscopic dielectric properties.

Next, we will then calculate the polarizabilities for each polarization mechanisms.