Scattering of light
- CBSE · NCERT Class 10, Ch 10 The Human Eye and the Colourful World
Scattering is the spreading of light in many directions when it strikes tiny particles, such as dust, smoke, water droplets or molecules of air.
When a beam of light passes through fine particles, they send some of it sideways. Then you can see the path of the beam. This is the Tyndall effect. You see it when sunlight enters a smoky room through a small hole, or falls through the mist in a dense forest.
The colour scattered depends on the size of the particles. Very fine particles, like molecules of air, scatter blue light far more than red. Larger particles scatter longer wavelengths too, and can make the light look white.
A small example
Red light has a wavelength about 1.8 times that of blue light. So air scatters the blue part of sunlight much more strongly than the red. That scattered blue reaches your eyes from every part of the sky, and the sky looks blue. Red is scattered least, so a red danger light can be seen from far away, even through fog or smoke.
Where marks go
Question 39 of CBSE's 2026-27 Science sample paper asks why the sky looks dark to an astronaut in space, for 1 mark. The 2026-27 Science marking scheme answer is short: there is no atmosphere to scatter sunlight.
The version for visually impaired students gives 2 marks for explaining the Tyndall effect in the atmosphere. It also gives 1 mark each for why stop signs are red and why the sky is blue. The scheme's answers link each effect to the particles or the wavelength. Scattering is not the same as dispersion. See how to write answers the scheme can mark.
Sources
Facts last checked against these sources on 30 September 2026.
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