Tyndall effect is the phenomenon by virtue of which a beam of light gets scattered after striking the particles that are present in its path. In simple words, the Tyndall effect is based on the scattering of light and is best demonstrated by colloidal solutions. It is named after an Irish physicist John Tyndall. The phenomenon of the Tyndall effect helps the path of light to be clearly visible.
Examples
1. Visible Rays of Sunlight
When the rays of the sunlight hit the dust particles, all the colours contained by the light wave get equally reflected. This is because the dust particles are significantly larger in size than the wavelength of the light wave. A similar phenomenon can be observed in a forest after heavy rainfall. The water molecules present in the atmosphere scatter the light. Hence, in both cases, the phenomenon of Tyndall scattering makes the path of the light clearly visible.
2. Scattering of Car Light in Fog
Fog is a visible layer of water vapours and ice crystals that is present above the surface of the earth. During foggy weather, the light rays emitted from the headlight of a car strike the particles contained by the fog and get scattered away, thereby allowing the observer to trace the path taken by the light to travel. Hence, the visible path of light that is emitted by the headlights of a car during foggy weather is a prominent example of the Tyndall effect.
3. Light Shined through Milk
When laser light is made to shine through a container that is filled with a mixture of milk and water, its path is clearly visible. This is because the particles of the resultant colloid are large in size than the wavelength of the light. The colloid consists of dispersed particles, i.e., the milk particles and the dispersion medium, i.e., the water. When the laser hits the particles of the colloid, it gets scattered due to the dispersed particles, thereby allowing the proper visibility of the path taken by the light to travel.
4. Blue Coloured Iris
Human eyes that appear blue in colour do not contain any colour pigments in them. The Iris is made up of two layers, the stroma, and the epithelium. In the case of blue eyes, the stroma is translucent in nature and does not contain any pigment. The white light is reflected by the stroma and gets scattered after undergoing reflection. The blue colour gets scattered more than the other colours because of its shorter wavelength. Hence, providing the blue colour to the eye, thereby contributing to yet another example of Tyndall scattering.
5. Smoke from Motorcycles
A very popular application of the Tyndall effect can be easily seen in the 2 strokes or 4 stroke engine of a motorcycle. The blue smoke coming out of such engines indicate that the light is getting scattered due to the Tyndall effect. The burning of the engine oil releases particles of smoke in the air that are bigger in size as compared to the wavelength of the light. Hence, the smoke coming out of such engines appear to be a little blue near the areas from where the smoke emerges out.
6. Opalescent Glass
Opalescent glass is a milky white or translucent glass. It is capable of displaying the Tyndall effect in the best possible manner. The light shined through such a glass appears orange in colour; however, the glass appears blue. This is because the composition of the opalescent glass consists of particles that scatter the light rays in an uneven manner.
7. Blue Colour of Sky
The atmosphere consists of a number of gases such as oxygen, nitrogen, carbon-di-oxide, etc. along with particles of dust and smoke. As per the Tyndall effect, when the sunlight strikes the gaseous, dust, or smoke particles, it gets scattered. As compared to the wavelength of sunlight, the dust and smoke particles are larger in size; therefore, the lights get evenly scattered and appear white in colour. When the sunlight strikes the particles of gases like oxygen and nitrogen that are smaller in size than the wavelength of the sunlight, the colours having smaller wavelengths, i.e., blue and violet, get much more scattered. Our senses tend to respond to the blue colour more than the violet. Hence, the sky appears blue.
