What are the parts of the human eye?

The human eye consists of cornea, pupil, lens, retina, iris, ciliary muscles, and optic nerve.

What are common defects of the eye and their correction?

Myopia, Hypermetropia, Presbyopia, and Astigmatism are corrected using concave or convex lenses.

What causes a rainbow?

A rainbow forms due to dispersion of sunlight by water droplets causing refraction, reflection, and splitting of colors.

2. What are rods and cones? How do they differ?

Rods: sensitive to low light, do not detect colour, concentrated at peripheral retina. Cones: less sensitive, responsible for colour vision and high acuity, concentrated in fovea (central retina).

3. Is the image formed on the retina upright or inverted? How do we see upright?

Image on retina is real and inverted. Brain interprets the signals and perceives the object upright — perception corrects inversion during visual processing.

13. What is dispersion of light by a prism and why does it occur?

Dispersion: splitting of white light into colours because refractive index of glass varies with wavelength (shorter wavelengths refract more). Order: red (least bent) → violet (most bent).

Human Eye & Colourful World | Class 10 Science Notes

📘 Introduction

This chapter explains Human Eye & Colourful World, covering eye structure, common defects, correction using lenses, dispersion of light, and rainbow formation. Perfect for NEET, SSC, Railway, and Police Bharti exams and Class 10 board preparation.

🔹 Key Concepts

Human Eye: Cornea, pupil, lens, retina, iris, ciliary muscles, optic nerve
Defects: Myopia, Hypermetropia, Presbyopia, Astigmatism
Correction: Concave and convex lenses
Dispersion of Light: Splitting of white light into seven colors
Rainbow: Formed due to refraction, reflection, and dispersion of sunlight in water droplets

📊 Chapter Summary Table

Concept	Definition / Formula	Use
Myopia	Short-sightedness, corrected with concave lens	Helps focus distant objects
Hypermetropia	Long-sightedness, corrected with convex lens	Helps focus near objects
Rainbow	Dispersion + Refraction + Reflection	Understanding spectrum of light

🧮 Practice Questions

Name the parts of the human eye. ➡ Show Answer
Cornea, pupil, lens, retina, iris, ciliary muscles, optic nerve
List common defects of human eye and their correction. ➡ Show Answer
Myopia — concave lens, Hypermetropia — convex lens, Presbyopia — convex lens, Astigmatism — cylindrical lens
How is a rainbow formed? ➡ Show Answer
By refraction, reflection, and dispersion of sunlight through water droplets splitting white light into seven colors.

Eye Structure Vision Defects Colour & Light Atmospheric Phenomena

NCERT Class 10 — Human Eye & Colourful World

4. What is accommodation of the eye?

5. Define near point and far point of the human eye.

6. What is myopia (short-sightedness) and how is it corrected?

7. What is hypermetropia (far-sightedness) and its correction?

8. What is presbyopia and how is it managed?

9. What is astigmatism and how is it corrected?

10. What is power of a lens and its unit?

11. Why are polarised sunglasses useful?

14. Why does the sky appear blue?

15. Why does the Sun appear red at sunrise and sunset?

16. What is the Tyndall effect and where is it seen?

18. Why does violet light deviate more than red in a prism or raindrop?

19. Why is the sky near the horizon paler or whitish compared to zenith?

20. Why do clouds appear white?

21. Why do some people have blue eyes even without blue pigment?

22. Why does an object's colour change under coloured light?

23. Why are leaves green and why do they change colour in autumn?

24. Why do some objects look glossy while others look matte?

25. What are complementary colours? Give examples and contexts.

26. Explain mirages (qualitative).

27. What does "Red sky at night, shepherd's delight; red sky in morning, shepherd's warning" refer to?

28. Why does the Moon not show colours like the sky?

29. Why is laser light used in eye surgery and why must the eyes be protected?

30. Do other animals see colours we can't? Example bees and UV.

31. Why do metals appear shiny?

32. What causes afterimages (staring at bright colours then seeing complementary colour)?

33. Why is red used for stop/traffic lights?

34. (Practical) How to find corrective lens power approximately for myopia?

35. Why is UV radiation harmful and how do we protect eyes/skin?

36. How do microscopes & telescopes use lenses to magnify?

37. What limits resolution of optical instruments?

38. Why do stars twinkle but planets generally do not?

39. Why do black objects heat up faster in sunlight?

40. Why do optical illusions deceive our vision?

41. What causes colour blindness (brief)?

42. What causes colours during twilight (deep red/purple after sunset)?

43. Why do animals' eyes shine at night (eye-shine)?

44. Why is red light used to preserve night vision (e.g., in maps, submarines)?

45. What is colour temperature (warm vs cool light) and its effect on perception?