Physics – 2.1.2 Particle model | e-Consult

Brownian motion is the random, erratic movement of particles suspended in a fluid (liquid or gas). This motion is directly caused by the continuous, random bombardment of the suspended particles by the faster-moving molecules of the fluid. The fluid molecules are constantly in motion, and their collisions with the suspended particles are uneven and unpredictable. This results in the suspended particles undergoing a zig-zag path, constantly changing direction.

The size of the particles affected by Brownian motion changes with temperature. As temperature increases, the average kinetic energy of the fluid molecules increases. This means the fluid molecules move faster and collide with the suspended particles with greater frequency and force. Consequently, the amplitude (maximum displacement) of the Brownian motion increases. Larger particles will experience a more noticeable displacement due to these stronger collisions. Therefore, Brownian motion is more pronounced at higher temperatures.