Lesson 3, Topic 3
What is Brownian motion?
Brownian motion is the random movement of small visible particles in a suspension
Caused by the unequal random bombardment of molecules of liquid or gas on the visible particles
The zigzag movement of pollen grains in still water
Random movement of dust particles in still air
Brownian motion as evidence for the particle theory
Brownian motion is evidence for particles in matter. It is the particles in the liquid moving and colliding with the pollen grain that makes them move.
Smoke particles move in the same way because they are being hit by particles in air