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The Boltzmann constant (k B or k) is the proportionality factor that relates the average relative thermal energy of particles in a gas with the thermodynamic temperature of the gas. [2] It occurs in the definitions of the kelvin (K) and the gas constant , in Planck's law of black-body radiation and Boltzmann's entropy formula , and is used in ...
Given such a constant k, the proportionality relation ∝ with proportionality constant k between two sets A and B is the equivalence relation defined by {(,): =}. A direct proportionality can also be viewed as a linear equation in two variables with a y-intercept of 0 and a slope of k > 0, which corresponds to linear growth.
The closely related reduced Planck constant, equal to / and denoted is commonly used in quantum physics equations. The constant was postulated by Max Planck in 1900 as a proportionality constant needed to explain experimental black-body radiation. [ 2 ]
The constant of proportionality, , is called the Stefan–Boltzmann constant. It has the value It has the value σ = 5.670 374 419 ... × 10 −8 W⋅m −2 ⋅K −4 .
The Planck relation [1] [2] [3] (referred to as Planck's energy–frequency relation, [4] the Planck–Einstein relation, [5] Planck equation, [6] and Planck formula, [7] though the latter might also refer to Planck's law [8] [9]) is a fundamental equation in quantum mechanics which states that the energy E of a photon, known as photon energy, is proportional to its frequency ν: =.
In physics, Hooke's law is an empirical law which states that the force (F) needed to extend or compress a spring by some distance (x) scales linearly with respect to that distance—that is, F s = kx, where k is a constant factor characteristic of the spring (i.e., its stiffness), and x is small compared to the total possible deformation of the spring.
Formally, the wavelength version of Wien's displacement law states that the spectral radiance of black-body radiation per unit wavelength, peaks at the wavelength given by: = where T is the absolute temperature and b is a constant of proportionality called Wien's displacement constant, equal to 2.897 771 955... × 10 −3 m⋅K, [1] [2] or b ...
where k B is the Boltzmann constant and e is the elementary charge. This empirical law is named after Gustav Wiedemann and Rudolph Franz, who in 1853 reported that κ/σ has approximately the same value for different metals at the same temperature. [2] The proportionality of κ/σ with temperature was discovered by Ludvig Lorenz in 1872. [3]