Brownian Motion

Brownian motion is defined as the random movement of the microscopic particles suspended in a fluid. The Brownian motion is a phenomenon in which the small particles suspended in a liquid tend to move in the pseudo-random paths through the liquid. It is the result of asymmetry in kinetic impacts of the molecules which make up the liquid. The liquid phase should have some temperature, meaning its molecules or atoms should be thermally excited, bumping into each other and the objects suspended within them. Brownian motion is the irregular and constant movement of small particles when they are suspended in the fluid or gas. Brownian motion takes place in liquids and gases due to the random motion of the molecules. There are 2 sorts of Brownian motions of the smoke particles. The more easily observed movement is that in which particles collide from place to place. There is a 2nd type of motion more difficult to observe, in which the large particles are found to be turned through different angles by impact of the molecules. This is known as rotational Brownian motion. Brownian motion is caused because of the effect, being independent of all the external factors, is ascribed to thermal motion of molecules of the fluid. These molecules are in the constant irregular motion having velocity proportional to the square root of temperature.

Small particles of matter suspended in fluid are buffeted about by the molecules of the fluid. Brownian motion is observed for the particles about 0.001 mm in diameter; these are enough small to share in thermal motion, yet large enough to be seen with the microscope or ultra microscope. These molecules are in constant irregular motion with the velocity proportional to square root of the temperature. Therefore Brownian movement is irregular random movement of microscopic particles in the fluid as a result of the continuous bombardment from molecules of surrounding medium. Einstein proved that the net forward displacement of suspended particles is directly associated to the number of molecules per gram atomic weight. In accordance to the theory, the temperature of a substance is proportional to average kinetic energy with which the molecules of substance are vibrating or moving.