The rate at which momentum undergoes this physical process is related to a fluid's kinematic viscosity. In a semiconductor at equilibrium, the current due to charge carrier drift is opposed by the current due to this process. This process is described as a random walk in the Brownian motion model. The flux associated to this stochastic process is proportional to the negative gradient of concentration, according to Fick's law. Unlike convection, this process does not entail bulk motion of substance. When a solvent moves, rather than a solute, this process is called osmo
The rate at which momentum undergoes this physical process is related to a fluid's kinematic viscosity. In a semiconductor at equilibrium, the current due to charge carrier drift is opposed by the current due to this process. This process is described as a random walk in the Brownian motion model. The flux associated to this stochastic process is proportional to the negative gradient of concentration, according to Fick's law. Unlike convection, this process does not entail bulk motion of substance. When a solvent moves, rather than a solute, this process is called osmosis. For 10 points, name this process in which particles migrate to regions of lower concentration. 
The rate at which momentum undergoes this physical process is related to a fluid's kinematic viscosity.
diffusion [accept Brownian motion until it is read; prompt on "osmosis"; prompt on "random walk"] 