A glass prism disperses white light into a spectrum of colours, but the eye's lens system does not produce rainbow-coloured vision even though both involve refraction. Explain why the eye's lens does not disperse light into colours the way a glass prism does.
Generated by claude-sonnet-4-6 · 2026-06-26 01:09 · grounding rag
Model Answer
A glass prism disperses white light because its two refracting surfaces are inclined to each other. Different colours (wavelengths) of light bend by different amounts — violet bends the most, red the least — causing them to emerge along separate paths, producing a spectrum.
The eye's lens has curved, symmetrical surfaces (not inclined like a prism). Although the lens refracts light, the refracting surfaces are arranged so that all colours are converged to (approximately) the same focal point on the retina, rather than being spread apart. Additionally, the lens forms a focused image, so colours do not separate into distinct bands. Thus, no dispersion is perceived.
Source: Chapter 10, Section 10.3 and 10.4
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Explanation
- The key distinction examiners look for: prism = inclined surfaces → colours emerge at different angles = dispersion; eye lens = curved converging surfaces → colours focused together = no dispersion visible.
- You don't need to know the biological term "chromatic aberration" for Class 10, but the physics reasoning (different angles of deviation for different colours in a prism vs. convergence by a lens) is what earns marks.
- The passage explicitly states that "different colours of light bend through different angles" in a prism and that the inclined faces cause deviation — use this language in your answer.