Describe the Tyndall effect. Which types of mixtures exhibit this effect, and why? Provide a common example where you might observe the Tyndall effect.

The Tyndall effect is the scattering of a beam of light by colloidal particles as it passes through a colloid. It is exhibited by colloids and some suspensions (when particles are not settled). Solutions do not show the Tyndall effect because their particles are too small to scatter light. Colloidal particles are large enough to scatter light but small enough not to settle.

A common example is the path of light visible when a sunbeam enters a dusty room, where dust particles (a type of colloid/suspension) scatter the light.