Brownian Motion and Diffusion

Abstract

The motion of a particle suspended in a viscous fluid results from fluctuating forces which are the consequence of collisions with molecul es of the fluid. As an example a sphere of 1 μm in diameter in air is subjected to 10 16 collisions per second. The details of Brownian movement cannot be predicted exactly, however, we may assume that the events (collisions, displacements, etc.) are random. Therefore ev en though we cannot know the details of the phenomenon, we can determine the average behavior.