What is a Unit Cell? Crystal structures are made up of repeating units of atoms in well defined locations in a lattice. In order to describe these structures, it is…
Year: 2020
Space Lattice
What is Space Lattice? The three-dimensional network of imaginary lines connecting the atoms is called the space lattice. A crystal is an arrangement in three dimensions of atoms or molecules…
Assumption of quantum theory of radiation
Fundamental assumptions of Quantum Mechanics In a particular representation and applied to a system consisting of a single, structure-less particle the fundamental assumptions of Quantum Mechanics are: The quantum state of…
Weins law and Rayleigh-Jeans law
The Rayleigh-Jeans Law: The Rayleigh-Jeans Law was a useful but not completely successful attempt at establishing the functional form of the spectra of thermal radiation. The energy density uν per…
Black Body Radiation Spectrum
Black Body Radiation: Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, emitted by a black body (an idealized opaque, non-reflective…
Dispersion and Attenuation
Dispersion: Dispersion, in wave motion, any phenomenon associated with the propagation of individual waves at speeds that depend on their wavelengths. Ocean waves, for example, move at speeds proportional to…
Bohr’s Quantization Rule
What is Bohr’s Quantization Rule? Bohr’s Quantization Rule: Of all possible circular orbits allowed by the classical theory, the electrons are permitted to circulate only in those orbits in which…
Einstein’s Coefficients
What are Einstein’s Coefficients? Einstein coefficients are mathematical quantities which are a measure of the probability of absorption or emission of light by an atom or molecule. The Einstein A…
Specific Rotation
What is Specific Rotation? Specific rotation, [α], is a fundamental property of chiral substances that is expressed as the angle to which the material causes polarized light to rotate at…
Concept Of Rest Mass of Photon
Concept Of Rest Mass of Photon Photons are said to be massless. The logic can be demonstrated as follows: Consider a “particle” accelerating to velocity v (a vector). As per…