What causes Brownian motion in colloidal dispersion?

(N/A) Brownian motion is caused by the unbalanced bombardment of the colloidal particles by the molecules of the dispersion medium. These molecules are in constant,rapid motion,similar to molecules in a gas. As a result of these collisions,the colloidal particles acquire kinetic energy comparable to that of the dispersion medium molecules,leading to their characteristic zig-zag motion.