Search results
Results From The WOW.Com Content Network
Boltzmann constant: The Boltzmann constant, k, is one of seven fixed constants defining the International System of Units, the SI, with k = 1.380 649 x 10 −23 J K −1. The Boltzmann constant is a proportionality constant between the quantities temperature (with unit kelvin) and energy (with unit joule).
These include the Boltzmann constant, which gives the correspondence of the dimension temperature to the dimension of energy per degree of freedom, and the Avogadro constant, which gives the correspondence of the dimension of amount of substance with the dimension of count of entities (the latter formally regarded in the SI as being dimensionless).
For thermal noise, its spectral density is given by N 0 = kT, where k is the Boltzmann constant in joules per kelvin (J/K), and T is the receiver system noise temperature in kelvins. The noise amplitude spectral density is the square root of the noise power spectral density, and is given in units such as volts per square root of hertz, V / H z ...
kT (also written as k B T) is the product of the Boltzmann constant, k (or k B), and the temperature, T.This product is used in physics as a scale factor for energy values in molecular-scale systems (sometimes it is used as a unit of energy), as the rates and frequencies of many processes and phenomena depend not on their energy alone, but on the ratio of that energy and kT, that is, on E ...
In common usage, the symbol used for radiant exitance (often called radiant emittance) varies among different texts and in different fields. The Stefan–Boltzmann law may be expressed as a formula for radiance as a function of temperature. Radiance is measured in watts per square metre per steradian (W⋅m −2 ⋅sr −1).
The proportionality constant k B is one of the fundamental constants of physics and is named the Boltzmann constant in honor of its discoverer. Boltzmann's entropy describes the system when all the accessible microstates are equally likely. It is the configuration corresponding to the maximum of entropy at equilibrium.
The Boltzmann equation can be used to determine how physical quantities change, such as heat energy and momentum, when a fluid is in transport. One may also derive other properties characteristic to fluids such as viscosity , thermal conductivity , and electrical conductivity (by treating the charge carriers in a material as a gas). [ 2 ]
where A is a constant based on the cross-sectional area of the interconnect, J is the current density, E a is the activation energy (e.g. 0.7 eV for grain boundary diffusion in aluminum), k is the Boltzmann constant, T is the temperature and n is a scaling factor (usually set to 2 according to Black).