Chapter 11 of Class 10 Science, The Human Eye and the Colourful World, explores how we see, how light behaves, and why the sky looks blue or stars twinkle. It combines biology and physics to explain vision, refraction, dispersion, and atmospheric phenomena.
At Convex Classes Jaipur, we provide complete NCERT solutions for this chapter — written in simple language, aligned with CBSE guidelines, and perfect for board exam preparation.
NCERT Questions and Answers – Chapter 11
Page 190 – Intext Questions
Q1. What is meant by power of accommodation of the eye?
👉 The ability of the eye lens to adjust its focal length to see nearby and distant objects clearly is called the power of accommodation.
Q2. A person with a myopic eye cannot see objects beyond 1.2 m clearly. What should be the type of corrective lens used to restore proper vision?
👉 A concave lens of suitable focal length should be used to correct myopia.
Q3. What is the far point and near point of the human eye with normal vision?
👉 Near point: 25 cm Far point: Infinity
Q4. A student has difficulty reading the blackboard while sitting at the back of the class. What could be the defect of vision? How can it be corrected?
👉 The student likely has myopia. It can be corrected using a concave lens.
Page 197 – Intext Questions
Q1. What is meant by refraction of light?
👉 Refraction is the bending of light when it passes from one medium to another due to change in speed.
Q2. Why do stars twinkle?
👉 Due to atmospheric refraction, starlight bends irregularly as it passes through layers of air with varying densities, causing the star to appear to twinkle.
Q3. Why don’t planets twinkle?
👉 Planets appear larger and their light passes through multiple paths, averaging out the fluctuations — so they don’t twinkle.
Q4. Why does the sun appear reddish at sunrise and sunset?
👉 During sunrise/sunset, sunlight travels a longer path through the atmosphere. Scattering removes shorter wavelengths (blue), leaving red light.
Page 198 – Intext Questions
Q1. Why does the sky appear blue?
👉 Due to scattering of light, shorter blue wavelengths scatter more than red, making the sky appear blue.
Q2. What is the difference in colours of the sun observed during sunrise/sunset and noon? Why?
👉 At noon, the sun appears white due to minimal scattering. During sunrise/sunset, it appears reddish due to maximum scattering of shorter wavelengths.
Page 199 – Exercise Questions
Q1. What is meant by power of accommodation?
👉 It is the eye’s ability to adjust the lens curvature to focus on near or distant objects.
Q2. A person with myopia cannot see distant objects clearly. What type of lens is used to correct this defect?
👉 A concave lens is used.
Q3. What is the far point of a person with myopia?
👉 Less than infinity — depends on the severity of the defect.
Q4. What are the causes of myopia?
👉 Elongation of eyeball or excessive curvature of the eye lens.
Q5. What are the causes of hypermetropia?
👉 Shortening of eyeball or insufficient curvature of the lens.
Q6. Explain the refraction of light through a prism.
👉 Light bends twice — once when entering and once when exiting the prism — causing dispersion into seven colours.
Q7. Describe the formation of rainbow in the sky.
👉 Caused by dispersion, refraction, and internal reflection of sunlight in water droplets.
Q8. Why do stars twinkle but not planets?
👉 Stars are point sources; their light fluctuates due to atmospheric refraction. Planets have larger apparent size, so fluctuations cancel out.
Q9. Why does the sun appear reddish at sunrise and sunset?
👉 Longer atmospheric path causes scattering of blue light, leaving red light to reach our eyes.
FAQs – Human Eye and Colourful World
Q1. What is the function of the retina?
👉 It receives focused light and converts it into electrical signals sent to the brain.
Q2. What is the role of ciliary muscles?
👉 They adjust the lens curvature to focus on near or far objects.
Q3. What is dispersion of light?
👉 Splitting of white light into its component colours when passing through a prism.
Q4. What causes the twinkling of stars?
👉 Atmospheric refraction due to varying air densities.
Q5. How is myopia corrected?
👉 Using a concave lens that diverges light rays before they enter the eye.
Conclusion
Chapter 11 beautifully blends biology and physics to explain how we see and perceive the world. With Convex Classes Jaipur, students get complete NCERT solutions, clear explanations, and exam-focused guidance — all in one place.
📌 Visit our website now to access full chapter notes, video lessons, and practice questions for Class 10 Science.
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