Brownian motion is shown using the Molecular Motion Demonstrator, a plastic chip, and small metal beads.


Teachable Topics:

  • Brownian Motion
  • Molecular Motion
  • Conservation of Momentum


Brownian motion describes the atomic motion that occurs from the random path molecules make when being bombarded by collisions with their fellow (usually smaller) molecules. The random nature of the collisions makes the path of the molecule impossible to predict.

The temperature of the gas directly affects Brownian motion due to the increase in the number and energy in the collisions.  


  • Molecular Motion Demonstrator
  • Red Disc
  • Ball Bearings


  1. Place the MMD onto a level surface
  2. Place the large red disc in the centre of the platform.
  3. Add several smaller metal ball bearings
  4. Turn on the MMD and watch the magic happen!

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