Exploring Mixtures and their Separation - Tyndall Effect

The Tyndall Effect is the phenomenon of scattering of a beam of light by colloidal particles or particles in a very fine suspension, making the path of light visible.

In a True Solution, the particle size is less than $1 \text{ nm}$ ($10^{-9} \text{ m}$). These particles are too small to scatter light; hence, true solutions do not show the Tyndall effect.

In a Colloid, the particle size ranges between $1 \text{ nm}$ and $1000 \text{ nm}$ ($10^{-9} \text{ m}$ to $10^{-6} \text{ m}$). These particles are large enough to scatter a beam of visible light.

In a Suspension, particles are larger than $1000 \text{ nm}$. They scatter light when they are suspended in the medium, but the effect disappears if the particles settle down due to gravity.

Common examples of the Tyndall effect include sunlight passing through a canopy of a dense forest (where mist acts as the colloid) and a beam of light entering a dark, dusty room through a small hole.

The visibility of the path of light depends on the wavelength of light and the size of the scattering particles.