The Tyndall effect is shown by colloidal particles. This occurs because the size of colloidal particles is roughly comparable to the wavelength of visible light (about 40 to 900 nanometers), which allows them to scatter light effectively as it passes through the colloid

. When light passes through a colloidal solution, the suspended particles scatter the light, making the path of the light beam visible. This scattering is the Tyndall effect. It is not observed in true solutions where particle sizes are much smaller than the wavelength of light (like glucose solution)

. Examples where the Tyndall effect is observed include:

• The visible beam of headlights in fog, where water droplets scatter light

• The blue color of the sky, caused by scattering of sunlight by atmospheric particles

• Smoke and smog, which are aerosols containing fine particles that scatter light

• Colloidal sols like gold sol, where particles scatter light

In summary, the Tyndall effect is characteristic of colloidal dispersions due to their particle size being close to the wavelength of light, causing light scattering that makes the light beam visible