Science glossary film: Brownian motion

The random movement of small, visible particles suspended in a liquid or gas when viewed under a microscope. One example of Brownian motion is the movement of smoke particles in air. This motion is caused by atoms or molecules in the air repeatedly colliding with the larger, visible smoke particles, causing them to jiggle around. The atoms and molecules are too small to see, even through a microscope, but Brownian motion provides proof of their existence. Here, we can see tiny mineral crystals, inside microscopic algae, being jiggled around by invisible water molecules.

One example of Brownian motion is the movement of smoke particles in air. This motion is caused by atoms or molecules in the air repeatedly colliding with the larger, visible smoke particles, causing them to jiggle around. The atoms and molecules are too small to see, even through a microscope, but Brownian motion provides proof of their existence. Here, we can see tiny mineral crystals, inside microscopic algae, being jiggled around by invisible water molecules.