Question

What is the Tyndall effect? Explain with an example.

Answer 1

Hint:The Tyndall effect is caused by particles in a colloid or an extremely tiny solution scattering light. It's similar to Rayleigh scattering in that the intensity of dispersed light is inversely proportional to the fourth power of the wavelength, therefore blue light scatters far more than red light. The blue colour visible in the smoke released by motorbikes, particularly two-stroke machines, where the burning engine oil provides these particles, is an example in everyday life.

Complete answer:
Longer wavelengths are more transmitted by the Tyndall effect, but shorter wavelengths are more diffusely reflected via scattering. When light-scattering particulate matter is spread in an otherwise light-transmitting medium, the Tyndall effect is observed when the diameter of an individual particle is in the range of \[40{\text{ }}to{\text{ }}900\] nm, i.e. somewhat below or around the wavelengths of visible light (\[400-750\]nm).

When a beam of light passes through a small hole in a smoke-filled dark room, its path becomes apparent to us. The small dust particles in the room's air scatter the light beam all over the place. As a result, light scattering makes the particles visible. When sunlight penetrates through a dense forest canopy, the Tyndall effect is seen. Light is scattered by small water droplets in the mist.

Note:Let us see some more important points regarding the Tyndall effect. The Tyndall effect is utilised in nephelometers to detect the size and density of particles in aerosols and other colloidal materials (see ultramicroscope and turbidimeter).