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Electron density or electronic density is the measure of the probability of an electron being present at an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial variables and is typically denoted as either ρ ( r ) {\displaystyle \rho ({\textbf {r}})} or n ( r ) {\displaystyle n ...
Let = 2.69 × 10 25 m −3, which is the Loschmidt constant, or particle density of Earth's atmosphere at standard pressure and temperature. At T {\displaystyle T} = 300 K , the ionization is essentially none: x {\displaystyle x} = 5 × 10 −115 and there would almost certainly be no ionized atoms in the volume of Earth's atmosphere.
The density of the Earth's atmosphere decreases nearly exponentially with altitude. The total mass of the atmosphere is M = ρ A H ≃ 1 kg/cm 2 within a column of one square centimeter above the ground (with ρ A = 1.29 kg/m 3 the atmospheric density on the ground at z = 0 m altitude, and H ≃ 8 km the average atmospheric scale height ).
The two-dimensional systems of vortices confined to a finite area can form thermal equilibrium states at negative temperature, [18] [19] and indeed negative temperature states were first predicted by Onsager in his analysis of classical point vortices. [20]
TEC plot for the continental USA, made on 2013-11-24. Total electron content (TEC) is an important descriptive quantity for the ionosphere of the Earth. TEC is the total number of electrons integrated between two points, along a tube of one meter squared cross section, i.e., the electron columnar 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.
The electron (e −, or β − in nuclear reactions) is a subatomic particle with a negative one elementary electric charge. [13] Electrons belong to the first generation of the lepton particle family, [14] and are generally thought to be elementary particles because they have no known components or substructure. [1]
Under the free electron model, the electrons in a metal can be considered to form a Fermi gas.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.