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One more general framework is the Maxwell–Stefan diffusion equations [9] of multi-component mass transfer, from which Fick's law can be obtained as a limiting case, when the mixture is extremely dilute and every chemical species is interacting only with the bulk mixture and not with other species. To account for the presence of multiple ...
Equations [ edit ] The Beer–Lambert law states that there is a logarithmic dependence between the transmission (or transmissivity), T, of light through a substance and the product of the absorption coefficient of the substance, α, and the distance the light travels through the material (i.e. the path length), ℓ.
An electromagnetic wave propagating along a path C has the phase shift over C as if it was propagating a path in a vacuum, length of which, is equal to the optical path length of C. Thus, if a wave is traveling through several different media, then the optical path length of each medium can be added to find the total optical path length. The ...
Schematic drawing of a molecule in a cylindrical pore in the case of Knudsen diffusion; are indicated the pore diameter (d) and the free path of the particle (l).Knudsen diffusion, named after Martin Knudsen, is a means of diffusion that occurs when the scale length of a system is comparable to or smaller than the mean free path of the particles involved.
(Oscillatory) displacement amplitude: Any quantity symbol typically subscripted with 0, m or max, or the capitalized letter (if displacement was in lower case). Here for generality A 0 is used and can be replaced. m [L] (Oscillatory) velocity amplitude V, v 0, v m. Here v 0 is used. m s −1 [L][T] −1 (Oscillatory) acceleration amplitude A, a ...
Their equations describing Brownian motion were subsequently verified by the experimental work of Jean Baptiste Perrin in 1908. The instantaneous velocity of the Brownian motion can be defined as v = Δ x /Δ t , when Δ t << τ , where τ is the momentum relaxation time.
The Nernst–Planck equation is a conservation of mass equation used to describe the motion of a charged chemical species in a fluid medium. It extends Fick's law of diffusion for the case where the diffusing particles are also moved with respect to the fluid by electrostatic forces.
In physics, mean free path is the average distance over which a moving particle (such as an atom, a molecule, or a photon) travels before substantially changing its direction or energy (or, in a specific context, other properties), typically as a result of one or more successive collisions with other particles.