Brownian motion

Definition

Brownian motion is the random, erratic movement of particles suspended in a fluid (liquid or gas) resulting from collisions with fast-moving molecules of the fluid. It provides evidence for the kinetic theory of gases and supports the concept of molecular motion.

5 Must Know Facts For Your Next Test

1. Brownian motion was first observed by botanist Robert Brown in 1827 while studying pollen grains in water.
2. The phenomenon can be explained by Einstein's theory, which correlates the displacement of particles with time due to thermal energy.
3. It provides evidence for the existence of atoms and molecules, reinforcing kinetic theory and atomic models.
4. Mathematically, Brownian motion can be described using a random walk model or diffusion equation.
5. In physics, it is crucial for understanding transport phenomena and is used in fields such as statistical mechanics and thermodynamics.

Review Questions

• Who first observed Brownian motion and in what year?
• How does Einstein's theory explain Brownian motion?
• Why is Brownian motion significant for supporting the kinetic theory of gases?

Related terms

Kinetic Theory: A theory that explains the macroscopic properties of gases based on the motions and interactions of individual molecules.

Diffusion: The process by which particles spread from an area of higher concentration to an area of lower concentration.

Random Walk: A mathematical model used to describe a path consisting of a succession of random steps, often used to model Brownian motion.