the human eye and the colourful world — Science STD 10 — Question
Gujarat BoardEnglish MediumSTD 10Sciencethe human eye and the colourful world3 Marks
Question
Describe the Tyndall effect.
✓
Answer
The earth’s atmosphere is a heterogeneous mixture of minute particles such as smoke particles, tiny water droplets, suspended dust particles and molecules of air.
When a beam of light strikes such ${ }^{\dagger} colloidal$ particles, the path of light beam becomes visible due to diffused light by these particles.
This phenomenon of scattering of light by the colloidal particles is known as the Tyndall effect.
Light rays reach us after the dispersion of light in all the directions from these particles.
Examples of the Tyndall effect:
$(1)$ When a fine beam of sunlight enters into a smoke filled room through a small hole, a spread path of the beam becomes visible.
$(2)$ When the sunlight enters a canopy of dense forest, the Tyndall effect is seen due to the scattering of light through tiny water droplets of mist.
$(3)$ Sometimes smoke emitted by the combustion of engine oil appears blue in colour due to the Tyndall effect.
This phenomenon is developed commercially to determine the size and density of aerosol and other colloidal particles.
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