Tyndall effect

The Tyndall effect occurs when light passes through a mixture containing tiny particles suspended in a liquid or gas. These particles are small enough to scatter the light, making the beam visible along its path. This is why, for example, a small stream of flashlight light can be seen in a foggy or smoky environment. The effect helps distinguish between a true solution (where particles are too small to scatter light) and a colloid or suspension, where particles are large enough to scatter light and create visible beams or halos.