The scattering of a beam of light by the particles of a colloid is called the Tyndall effect. When we apply torch light on a glass of milk then the path of the light becomes visible but it is not so in case of water because in milk light is scattered by its very fine particles.
Tyndall effect can be observed when sunlight passes through the canopy of a dense forest. In the forest, mist contains tiny droplets of water, which act as particles of colloid dispersed in air.