Particle flux density
The particle current density j denotes the number N of particles (e.g. atoms , molecules , quasiparticles ) that move through an area A in the time interval dt
The particle flow I is included
- .
The cause of the movement can be diffusion , as in Fick's law . In the case of electrical conduction , in which the electrons move through the surface in both directions, but a net share flows in one direction, there remains a drift with which the electrons move through the surface.
The particle flux density can also be defined as the product of the particle density and the speed of the particles,
where is the mean speed (e.g. the drift speed ) of the particles. The above scalar expression is then obtained by integrating over the area . The scalar product between and the normal component of the surface element ( ) is taken at each point :
See also
Web links
- Jürgen Schatz, Robert Tammer: Chemistry and Physics for Physicians .
- Particle flux density , University of Graz.