Chapter 10: The Human Eye and the Colourful World
Simple, exam-focused CBSE Class 10 Science notes — star topics, concepts, common mistakes, and previous year question patterns, all on one page.
Chapter 10: The Human Eye and the Colourful World
⭐ Star Topics / Most Important
- Structure of the human eye
- Myopia, hypermetropia, presbyopia (defects and corrections)
- Dispersion of light through a prism
- Scattering of light — why sky is blue, sunset is red
Detailed Chapter Notes
Light enters via the cornea (does most refraction), through the pupil (controlled by the iris), then the eye lens (fine-tunes focus) forms a real, inverted image on the retina, sent to the brain via the optic nerve.
Power of accommodation lets the eye lens adjust focal length via ciliary muscles. Near point ~25 cm, far point infinity.
Myopia (near-sightedness): image forms in front of retina, corrected with a concave lens. Hypermetropia (far-sightedness): image forms behind retina, corrected with a convex lens. Presbyopia: age-related, corrected with bifocal lenses.
Dispersion: white light splits into VIBGYOR through a prism since each colour bends by a different amount (violet most, red least) — same reason rainbows form using water droplets.
Scattering: Tyndall effect (scattering by particles in a colloid/suspension). Sky appears blue because air molecules scatter blue light (shorter wavelength) more. At sunrise/sunset, light travels through more atmosphere, so blue is scattered away, leaving red/orange.
Easy memory trick: "Myopia = Minus" (concave, negative power). A common wrong claim is "sky is blue because it reflects the ocean" — the correct reason is Rayleigh scattering of shorter wavelength blue light by atmospheric particles.
Search on YouTube: Human eye defects and correction Class 10 diagram for a visual walkthrough of this chapter.
- Draw a labelled diagram of the human eye (3 marks)
- A person can see nearby objects but not distant objects. Name the defect and lens used for correction (2 marks)
- Why does the sun appear reddish at sunrise and sunset? (2/3 marks)
- What is the Tyndall effect? Give one everyday example (2 marks)
- Explain the dispersion of white light through a glass prism with a diagram (3 marks)