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The number density (symbol: n or ρ N) is an intensive quantity used to describe the degree of concentration of countable objects (particles, molecules, phonons, cells, galaxies, etc.) in physical space: three-dimensional volumetric number density, two-dimensional areal number density, or one-dimensional linear number density.
Charge carrier density, also known as carrier concentration, denotes the number of charge carriers per volume. In SI units, it is measured in m −3. As with any density, in principle it can depend on position. However, usually carrier concentration is given as a single number, and represents the average carrier density over the whole material.
Spin density is electron density applied to free radicals. It is defined as the total electron density of electrons of one spin minus the total electron density of the electrons of the other spin. One of the ways to measure it experimentally is by electron spin resonance, [14] neutron diffraction allows direct mapping of the spin density in 3D ...
The formula for evaluating the drift velocity of charge carriers in a material of constant cross-sectional area is given by: [1] =, where u is the drift velocity of electrons, j is the current density flowing through the material, n is the charge-carrier number density, and q is the charge on the charge-carrier.
The number density / of conduction electrons in metals ranges between approximately 10 28 and 10 29 electrons/m 3, which is also the typical density of atoms in ordinary solid matter. This number density produces a Fermi energy of the order of 2 to 10 electronvolts. [2]
The number density of the electron gas was assumed to be =, where Z is the effective number of de-localized electrons per ion, for which Drude used the valence number, A is the atomic mass per mole, [Ashcroft & Mermin 10] is the mass density (mass per unit volume) [Ashcroft & Mermin 10] of the "ions", and N A is the Avogadro constant.
where ℓ is the mean free path, n is the number of target particles per unit volume, and σ is the effective cross-sectional area for collision. The area of the slab is L 2, and its volume is L 2 dx. The typical number of stopping atoms in the slab is the concentration n times the volume, i.e., n L 2 dx. The probability that a beam particle ...
A simple derivation of the Boltzmann relation for the electrons can be obtained using the momentum fluid equation of the two-fluid model of plasma physics in absence of a magnetic field. When the electrons reach dynamic equilibrium , the inertial and the collisional terms of the momentum equations are zero, and the only terms left in the ...