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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.
This force is balanced by the electron degeneracy pressure keeping the star stable. [4] In metals, the positive nuclei are partly ionized and spaced by normal interatomic distances. Gravity has negligible effect; the positive ion cores are attracted to the negatively charged electron gas. This force is balanced by the electron degeneracy pressure.
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.
The cosmological constant has the same effect as an intrinsic energy density of the vacuum, ρ vac (and an associated pressure). In this context, it is commonly moved to the right-hand side of the equation using Λ = κρ vac. It is common to quote values of energy density directly, though still using the name "cosmological constant".
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.
In condensed matter physics, the Fermi surface is the surface in reciprocal space which separates occupied electron states from unoccupied electron states at zero temperature. [1] The shape of the Fermi surface is derived from the periodicity and symmetry of the crystalline lattice and from the occupation of electronic energy bands.
In theoretical physics, negative mass is a hypothetical type of exotic matter whose mass is of opposite sign to the mass of normal matter, e.g. −1 kg. [1] [2] Such matter would violate one or more energy conditions and exhibit strange properties such as the oppositely oriented acceleration for an applied force orientation.