Class 10 / Science
Class 10 Science Human Eye and Colourful World Notes
Notes on human eye, defects of vision, correction, dispersion, atmospheric refraction, and scattering.
Topic introduction
Human Eye and Colourful World connects vision, lenses, atmospheric refraction, dispersion, and scattering. Students should learn both the eye-defect corrections and the reason behind natural phenomena like blue sky and red sunsets.
Key points
- The eye lens focuses light on the retina to form an image.
- Myopia is corrected using a concave lens.
- Hypermetropia is corrected using a convex lens.
- Scattering of light explains the blue colour of the sky and reddish appearance of the sun at sunrise and sunset.
Definitions
Retina: The light-sensitive screen inside the eye where the image is formed.
Accommodation: The ability of the eye lens to change focal length to focus near and distant objects.
Myopia: A defect in which distant objects are not seen clearly.
Hypermetropia: A defect in which nearby objects are not seen clearly.
Dispersion: Splitting of white light into its component colours.
Examples
- Myopia is corrected using a concave lens.
- Hypermetropia is corrected using a convex lens.
- A prism can split white light into seven colours.
- The sky appears blue because shorter blue wavelengths scatter more strongly.
Eye and vision defects
Accommodation is the ability of the eye lens to adjust focal length.
Common defects include myopia, hypermetropia, and presbyopia.
Colourful world
Dispersion splits white light into its component colours.
Atmospheric refraction and scattering explain several natural phenomena.
Common mistakes
- Interchanging the correction lenses for myopia and hypermetropia.
- Writing image forms on the lens instead of retina.
- Confusing dispersion with scattering.
- Forgetting that red light scatters less and travels farther through the atmosphere.
- Explaining atmospheric refraction without mentioning changing air density.
Quick practice
- What is power of accommodation?
- Which lens corrects myopia?
- Why is the sky blue?
- What is dispersion?
Related practice
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