CBSE Class 10 Science Chapter 10 The Human Eye and the Colorful World

The Human Eye and the Colorful World is a chapter in your science subject. Radhe Radhe to all my dear children! You all will have to work very hard for your board exams to get good marks. In this post, I will try to cover all the important topics of your 10th-grade science syllabus so that you can understand and remember them.

The Human Eye and the Colorful World, which is your tenth chapter, falls under the physics section of science. All the information you need to study in this chapter will be found in this post.

Also Read- CBSE Class 10 Science Chapter 9 Light – Reflection and Refraction

Key Content of Chapter 10 The Human Eye and the Colorful World

👁️ 1. The Human Eye

• Human eye is a sense organ that helps us see objects and colours.
• It works like a camera.
• Light enters the eye through cornea.
• The eye lens focuses light on the retina.
• Retina has light-sensitive cells that convert light into electrical signals.
• These signals are sent to the brain through the optic nerve.
• Brain interprets these signals and forms the image.

👁️‍🗨️ 2. Power of Accommodation

• The eye lens can change its focal length.
• This ability is called power of accommodation.
• Ciliary muscles control the curvature of the eye lens.
• For distant objects → lens becomes thin → focal length increases.
• For nearby objects → lens becomes thick → focal length decreases.
• Near point of normal eye = 25 cm.
• Far point of normal eye = infinity.

⚠️ 3. Defects of Vision and Their Correction

(a) Myopia (Near-sightedness)

• Person sees near objects clearly, but distant objects blurred.
• Image forms in front of retina.
• Causes:
  • Excessive curvature of eye lens
  • Elongation of eyeball
• Corrected using a concave lens.

(b) Hypermetropia (Far-sightedness)

• Person sees distant objects clearly, but near objects blurred.
• Image forms behind the retina.
• Causes:
  • Long focal length of eye lens
  • Short eyeball
• Corrected using a convex lens.

(c) Presbyopia

• Occurs due to ageing.
• Power of accommodation decreases.
• Near point shifts away.
• Corrected using bifocal lenses:
  • Upper part → concave lens (distant vision)
  • Lower part → convex lens (near vision)

🔺 4. Refraction of Light Through a Prism

• A prism has two triangular bases and three rectangular faces.
• Light bends at both refracting surfaces.
• Emergent ray is not parallel to incident ray.
• The angle between incident and emergent ray is called angle of deviation.

🌈 5. Dispersion of White Light

• White light splits into seven colours (VIBGYOR).
• This phenomenon is called dispersion.
• Violet bends the most, red bends the least.
• The band of colours formed is called spectrum.
• Newton proved that sunlight is made of seven colours.

🌧️ 6. Formation of Rainbow

• Rainbow is formed due to:
  1. Refraction of sunlight
  2. Dispersion
  3. Total internal reflection inside water droplets
• Water droplets act like tiny prisms.
• Rainbow is always seen opposite to the Sun.

🌬️ 7. Atmospheric Refraction

• Refraction of light by layers of atmosphere.
• Causes:
  • Twinkling of stars
  • Advance sunrise
  • Delayed sunset
• Sun is visible 2 minutes earlier at sunrise and 2 minutes later at sunset.

✨ 8. Twinkling of Stars

• Stars appear to twinkle due to atmospheric refraction.
• Stars are very far and act as point sources.
• Changing refractive index of air bends light continuously.

🪐 9. Why Planets Do Not Twinkle?

• Planets are closer to Earth.
• They appear as extended sources.
• Fluctuations in light cancel out.

🌌 10. Scattering of Light

• Scattering occurs due to tiny particles in the atmosphere.
• Tyndall effect: scattering of light by colloidal particles.

🔵 11. Why is the Sky Blue?

• Air molecules scatter shorter wavelength (blue light) more.
• Blue light reaches our eyes → sky appears blue.
• In absence of atmosphere, sky would look dark.

🔴 12. Why Sun Appears Red at Sunrise and Sunset?

• Sunlight travels longer path through atmosphere.
• Blue light is scattered away.
• Only red light reaches the eye.

🚦 13. Why Danger Signals are Red?

• Red light has longest wavelength.
• Least scattered by fog or smoke.
• Visible from long distances.

Also Read- CBSE Class 10 Science Chapter 4 Carbon and Its Compounds

Class 10 Science Chapter 10 The Human Eye and the Colorful World Notes

Science Chapter 10 The Human Eye and the Colorful World MCQs

Also Read- CBSE Class 10 Science Chapter 6 Control and Coordination

FAQs About The Human Eye and the Colorful World