The Tyndall effect is the scattering of light by colloidal particles when a beam of light passes through a colloidal solution. Because the colloidal particles are large enough to scatter light but small enough to remain suspended, the path of the light becomes visible.
It was discovered by John Tyndall in the 19th century.
Key Points about the Tyndall Effect:
- It occurs in colloidal solutions and very fine suspensions, but not in true solutions (like sugar solution) because the particles in true solutions are too small to scatter light.
- The scattered light makes the light beam visible from the side.
- The intensity of scattering depends on the size of the colloidal particles and the wavelength of light.
- It is used to distinguish between a colloidal solution and a true solution.
Examples of the Tyndall Effect:
- Sunlight streaming through a forest, where dust and water particles scatter light.
- Visible light beams in a movie theater (due to dust and smoke in the air).
- Headlights of a car on a foggy night.
- Milk in water showing a bluish color under sunlight.
In short, the Tyndall effect is the scattering of light by colloidal particles, making the path of the light beam visible.