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Why does the sky appear blue during the day?
AAir molecules emit blue light by common convention
BBlue light is scattered more than red light by air molecules
CSunlight contains only blue light at noon
DStars emit blue background light
Answer & Solution
Correct answer: B. Blue light is scattered more than red light by air molecules
1. Sunlight contains all colours from violet to red.
2. Scattering by air molecules is stronger for shorter wavelengths.
3. Blue light is scattered far more than red light by atmospheric gas molecules.
4. Scattered blue light reaches the eye from all directions in the sky.
5. So the daytime sky looks blue.
6. Rayleigh's law (1 / lambda^4) describes the scattering quantitatively.
_Source: NCERT Class 10 Science Ch 11 'Human Eye and the Colourful World'_
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