Science — CBSE Class 10 board question

Scattering of light: When sunlight strikes fine particles in the atmosphere, the light gets redirected in different directions. This phenomenon is called scattering of light.

Blue sky: The fine particles and air molecules in the atmosphere are smaller than the wavelength of visible light. They scatter blue light (shorter wavelength) much more strongly than red light. This scattered blue light enters our eyes, making the sky appear blue.

Source: Chapter 10, Section 10.6.2

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• Define scattering briefly (1 mark), then explain blue sky using the concept of wavelength-dependent scattering (1 mark).
• Key phrase: "shorter wavelengths (blue) are scattered more strongly."
• Avoid writing about Tyndall effect in detail — it wastes words here.
• Remember: red light has wavelength ~1.8 times greater than blue, so it scatters least — this is why the sky is blue, not red.