Tyndall Effect

One of the best ways to distinguish a solution from a colloidal dispersion is to use a strong beam of intense light. As the beam passes through a colloidal dispersion, it leaves a bright definite path, as the result of  scattering or diffusing of light rays by their deflection from the surface of colloidal particles. This is known as Tyndall effect. The particles may not be visible, but their presence and motion may be detected by the nature of the reflections. An important property of a colloid is this movement of the colloidal particles, brought about by the bombardment of thousand of molecules in the gas or liquid in which they are suspended.