Physical constants Physical constants Avogadro's number, also called Avogadro's Constant (NA) is a large constant used in chemistry and physics. Avogadro's number is formally defined as the number of carbon-12 atoms in 12 grams (0.012 kg) of carbon-12, which is approximately 6.023 . Historically, carbon-12 was chosen as the reference substance because its atomic mass could be measured particularly accurately. ...more on Wikipedia about "Avogadro's number"
In atomic physics, the Bohr magneton (symbol ) is named after the physicist Niels Bohr. ...more on Wikipedia about "Bohr magneton"
In the Bohr model of the structure of an atom, put forward by Niels Bohr in 1913, electrons orbit a central nucleus. The model says that the electrons orbit only at certain distances from the nucleus, depending on their energy. In the simplest atom, that of hydrogen, a single electron orbits, and the smallest possible orbit for the electron, that with the lowest energy, is the one at a distance from the nucleus called the Bohr radius. ...more on Wikipedia about "Bohr radius"
The characteristic impedance of vacuum or characteristic impedance of free space (Z0) is a physical constant, the characteristic impedance of electromagnetic radiation in vacuum, defined by: ...more on Wikipedia about "Characteristic impedance of vacuum"
The classical electron radius, also known as the Compton radius or the Thomson scattering length is based on a classical (i.e., non- quantum) relativistic model of the electron. Its value is calculated as ...more on Wikipedia about "Classical electron radius"
The electric constant () is the permittivity of vacuum, a physical constant, defined by: ...more on Wikipedia about "Electric constant"
The elementary charge (symbol e or sometimes q) is the electric charge carried by a single proton, or equivalently, the negative of the electric charge carried by a single electron. ...more on Wikipedia about "Elementary charge" Things Go Better with www.shortopedia.com.
In physics and chemistry, the Faraday constant is the amount of electric charge in one mole of electrons. The Faraday constant was named after British scientist Michael Faraday. It is used in electrolytic system calculations to determine the mass of a chemical species that will collect at an electrode. ...more on Wikipedia about "Faraday constant"
The gas constant (also known as the universal or ideal gas constant, usually denoted by symbol R) is a physical constant used in equations of state to relate various groups of state functions to one another. ...more on Wikipedia about "Gas constant"
(Gaussian gravitational constant) : k = 0.01720209895 A3/2 S−1/2 D−1. ...more on Wikipedia about "Gaussian gravitational constant"
A Hartree (symbol Eh) is the atomic unit of energy and is named after physicist Douglas Hartree. ...more on Wikipedia about "Hartree energy"
The Loschmidt number can be either an archaic name for Avogadro's constant, or the number density of an ideal gas at standard temperature and pressure in cubic centimeters. The value of the latter definition is: ...more on Wikipedia about "Loschmidt number"
The magnetic constant () is the permeability of vacuum. It is a physical constant not defined by other physical constants. ...more on Wikipedia about "Magnetic constant"
In science, a physical constant is a physical quantity whose numerical value does not change. It can be contrasted with a mathematical constant, which is a fixed value that does not directly involve a physical measurement. ...more on Wikipedia about "Physical constant"
The Planck mass is the natural unit of mass, denoted by mP. It is the mass for which the Schwarzschild radius is equal to the Compton length divided by π. ...more on Wikipedia about "Planck mass"
The Planck temperature, named after German physicist Max Planck, is the natural unit of temperature, denoted by TP. The Planck units, in general, represent limits of quantum mechanics. Talking about anything being "hotter" than the Planck temperature doesn't make a lot of sense; it is the temperature at which black holes are theorized to evaporate and the temperature at which the Universe "started" and cooled down from there, according to current cosmology. It is difficult to imagine anything being hotter than the Big Bang. ...more on Wikipedia about "Planck temperature"
Named after Max Planck, in physics Planck time is the natural unit of time, denoted by tP. It is considered the smallest possible measurement of time. ...more on Wikipedia about "Planck time"
The Rydberg constant is named after physicist Janne Rydberg, and is a physical constant discovered when measuring the spectrum of hydrogen, and building upon results from Anders Jonas Ångström and Johann Balmer. Each chemical element has its own Rydberg constant, which can be derived from the "infinity" Rydberg constant. ...more on Wikipedia about "Rydberg constant"
The Stefan-Boltzmann constant (also Stefan's constant), denoted with a Greek letter σ, is a derivable physical constant, the constant of proportionality between the total energy radiated per unit surface area of a black body in unit time and the fourth power of the thermodynamic temperature, as per the Stefan-Boltzmann law. ...more on Wikipedia about "Stefan-Boltzmann constant"
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