ASSIGNMENT NO 1 ( SOLID STATE PHYSICS 2 )
- What is meant by polarization mechanisms in dielectrics? Discuss the different polarization
mechanism in dielectrics and explain their temperature dependence.
Polarization is when the atoms or molecules in a material start to line up in a certain way when you apply an electric field to them. This makes the material act like it has its own tiny magnets, even if it’s not actually made of magnetic materials.
Polarization mechanisms in dielectrics refer to how atoms or molecules respond to electric fields, leading to material polarization. These mechanisms include electronic, ionic, dipolar, orientation, and space charge polarizations. Electronic polarization is relatively temperature-insensitive, while ionic and dipolar polarizations decrease with increasing temperature due to increased thermal motion. Orientation polarization is highly temperature-dependent, as orderly molecular arrangements are disrupted. Space charge polarization’s temperature dependence varies based on charge carrier mobility and interface properties.
- Explain polarization in dielectrics. Arrive at the relation between the dielectric constant and atomic
polarizability.
In dielectrics, polarization occurs when an external electric field is applied, causing the alignment or reorientation of the atoms or molecules within the material. This alignment results in the separation of positive and negative charges, creating an induced electric dipole moment in each atom or molecule.
The dielectric constant, often denoted by ε, is a measure of a material’s ability to store electrical energy in an electric field. It quantifies how much the presence of the material affects the electric field. Mathematically, the dielectric constant is defined as the ratio of the permittivity of the material (εr) to the permittivity of free space (ε0), where ε=εrε0.
The relation between the dielectric constant and atomic polarizability can be derived from the Clausius-Mossotti relation, which describes the polarizability of atoms or molecules in a dielectric material. The Clausius-Mossotti relation is given by:
ε+2/ε−1=Nα(alpha)/3ε0
