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Given that a system obeys detailed balance, the theorem is a proof that thermodynamic fluctuations in a physical variable predict the response quantified by the admittance or impedance (in their general sense, not only in electromagnetic terms) of the same physical variable (like voltage, temperature difference, etc.), and vice versa.
A dispersion relation relates the wavelength or wavenumber of a wave to its frequency. Given the dispersion relation, one can calculate the frequency-dependent phase velocity and group velocity of each sinusoidal component of a wave in the medium, as a function of frequency
The convection–diffusion equation can be derived in a straightforward way [4] from the continuity equation, which states that the rate of change for a scalar quantity in a differential control volume is given by flow and diffusion into and out of that part of the system along with any generation or consumption inside the control volume: + =, where j is the total flux and R is a net ...
The diffusion equation is a parabolic partial differential equation. In physics, it describes the macroscopic behavior of many micro-particles in Brownian motion , resulting from the random movements and collisions of the particles (see Fick's laws of diffusion ).
In a semiconductor with an arbitrary density of states, i.e. a relation of the form = between the density of holes or electrons and the corresponding quasi Fermi level (or electrochemical potential) , the Einstein relation is [11] [12] =, where is the electrical mobility (see § Proof of the general case for a proof of this relation).
Burgers' equation or Bateman–Burgers equation is a fundamental partial differential equation and convection–diffusion equation [1] occurring in various areas of applied mathematics, such as fluid mechanics, [2] nonlinear acoustics, [3] gas dynamics, and traffic flow. [4]
This path difference is (+) (′). The two separate waves will arrive at a point (infinitely far from these lattice planes) with the same phase , and hence undergo constructive interference , if and only if this path difference is equal to any integer value of the wavelength , i.e. n λ = ( A B + B C ) − ( A C ′ ) {\displaystyle n\lambda ...
Each gradient provides a thermodynamic force that moves the species present, and the Onsager reciprocal relations govern the relationship between the forces and the motions. Diffusiophoresis is a special case of multicomponent diffusion. Multicomponent diffusion is diffusion in mixtures, and diffusiophoresis is the special case where we are ...