Differentiate between dispersion and scattering of light. How does the size of particles determine the colour of scattered light?
Generated by claude-sonnet-4-6 · 2026-06-26 01:08 · grounding rag
Model Answer
Dispersion vs Scattering:
| Dispersion | Scattering |
|---|---|
| Splitting of white light into its component colours by a prism | Redirection of light in all directions by fine particles in a medium |
| Due to different refractive indices for different wavelengths | Due to interaction of light with suspended particles |
Effect of particle size on colour of scattered light:
- Very fine particles (smaller than the wavelength of visible light) scatter mainly blue light (shorter wavelength) — this is why the sky appears blue.
- Larger particles scatter light of longer wavelengths (yellow, red).
- If particles are very large, the scattered light may appear white.
Source: Chapter 10, Section 10.6 / 10.6.1
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Explanation
- Examiners expect a clear distinction between the two phenomena (1 mark) and then 2 marks for the particle-size effect with at least three levels: fine → blue, larger → longer wavelengths, very large → white.
- Use the sky example to illustrate fine-particle scattering — it shows you understand application.
- Do not confuse dispersion (prism/refraction-based) with scattering (particle-based); this is the core distinction the question tests.