Einstein relation (Electrical mobility equation)


Electrical mobility is the ability of charged particles (such as electrons or protons) to move through a medium in response to an electric field that is pulling them. The separation of ions according to their mobility in gas phase is called Ion mobility spectrometry, in liquid phase it is called electrophoresis. Mobility is related to the species’ diffusion coefficient through an exact (thermodynamically required) equation known as the Einstein relation. The Electrical mobility equation, for diffusion of charged particles relates the electrical mobility to the diffusion coefficient.

Related formulas


μElectrical mobility (m2/V*s)
q The electrical charge of the particle (coulomb)
kBBoltzmann constant
TThe gas temperature (K)
DThe diffusion coefficient (m2/s)