Encyclopedic Dictionary of Polymers

2011 Edition
| Editors: Jan W. Gooch

Brownian Motion

  • Jan W. Gooch
Reference work entry
DOI: https://doi.org/10.1007/978-1-4419-6247-8_1625
\ braú-nē-әn-\ n [Robert Brown † 1858 Scottish botanist] (ca. 1889) Refers to the continual movement of extremely small particles suspended in a fluid. The accepted explanation is that movement of the particles is due to bombardment by molecules of the fluid. The average length of path L followed by a particle in any given direction at a given time t is directly proportional to the square root of the absolute temperature T and the time t; it is also inversely proportional to the square root of the viscosity η of the medium and to the diameter d of the particle (Avogadro’s number N and the gas constant R enter in as constants):
$$L = {{2R} \over N}\sqrt {{{T \cdot t} \over {\eta d3\pi }}} $$
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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Jan W. Gooch
    • 1
  1. 1.AtlantaUSA