Home

NCERT Solutions for Class 10 Science Chapter 11 Human Eye an...

NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World

Author at PW

September 11, 2025

NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World:- NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World help students understand one of the most interesting parts of Physics. This chapter explains the structure of the human eye, how it works, and why we are able to see objects clearly at different distances. It also talks about common eye defects such as myopia and hypermetropia, and how they are corrected with the right type of lenses. Going through the human eye and colourful world question answer gives students clarity on topics like accommodation of the eye, least distance of distinct vision, twinkling of stars, scattering of light, and the reddish colour of the sun during sunrise and sunset.

When students read the human eye and the colourful world question answer, they get a clear picture of both theoretical concepts and their practical importance. The chapter also explains why planets do not twinkle and why astronauts see a dark sky instead of a blue one. Practising the human eye and colourful world question answer class 10 is important because all the concepts are directly linked with what is asked in exams. These solutions cover every area mentioned in the NCERT book, making it easier for students to revise and build confidence while preparing. Get the NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World below.

Check Out: CBSE Class 10 Books

NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World

Get the full and detailed NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World here:-

1. What is meant by power of accommodation of the eye?

Answer- The ability of the eye's lens to change its focal length to clearly focus on objects both near and far on the retina is called the power of accommodation. This process allows us to see clearly at different distances without needing corrective lenses.

2. A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of corrective lens used to restore proper vision?

Answer- An individual with myopia, or nearsightedness, can restore clear vision by using a concave lens. For this condition, a concave lens with a focal length of 1.2 meters is recommended. This type of lens helps to diverge light rays, allowing them to focus correctly on the retina and improve distance vision.

3. What is the far point and near point of the human eye with normal vision?

Answer- The near point of the eye is the closest distance at which an object can be seen clearly without any strain. For a typical human eye, this distance is 25 cm. On the other hand, the far point of the eye is the furthest distance at which an object can be seen clearly. For a normal, healthy eye, this distance is considered to be at infinity.

4. A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?

Answer- The student is experiencing short-sightedness, also known as myopia. Myopia can be corrected using a concave or diverging lens with the right power. This type of lens helps to focus distant objects correctly on the retina, allowing the student to see clearly at far distances.

NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World Page No.197

1. The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to

(a) presbyopia

(b) accommodation

(d) far-sightedness

Answer-

(b) accommodation Due to the process of accommodation, the human eye can focus on objects at varying distances by adjusting the focal length of the eye lens. This adjustment allows the eye to see both near and distant objects clearly by changing the shape of the lens to focus light properly on the retina.

NCERT Solutions for Class 10 Science Chapter 11 Human Eye and Colourful World Page No. 198

2. The human eye forms an image of an object at its

(a) cornea

(b) iris

(d) retina

Answer –

(d) retina The retina is the layer of nerve cells lining the back wall inside the eye. This crucial layer senses light and converts it into electrical signals, which are then sent to the brain. These signals are interpreted by the brain to create the visual images we see.

3. The least distance of distinct vision for a young adult with normal vision is about

(a) 25 m

(b) 2.5 cm

(d) 2.5 m

Answer –

(c) 25 cm For a young adult with normal vision, 25 cm is considered the least distance for distinct vision. This means that any object closer than 25 cm cannot be seen clearly without straining the eyes.

4. The change in focal length of an eye lens is caused by the action of the

(a) pupil

(b) retina

(d) iris

Answer-

(c) ciliary muscles The ciliary muscles control the eye's lens, adjusting its focal length to focus on objects at various distances. When these muscles contract or relax, they alter the shape of the lens, allowing it to focus light accurately on the retina for clear vision.

5. A person needs a lens of power -5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting (i) distant vision, and (ii) near vision?

Answer- The power ( P) of a lens of focal length f is given by the relation Power (P) = 1/ f (i) Power of the lens (used for correcting distant vision) = – 5.5 D Focal length of the lens ( f) = 1/ P f = 1/-5.5 f = -0.181 m The focal length of the lens (for correcting distant vision) is – 0.181 m. (ii) Power of the lens (used for correcting near vision) = +1.5 D Focal length of the required lens ( f) = 1/ P f = 1/1.5 = +0.667 m The focal length of the lens (for correcting near vision) is 0.667 m.

6. The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?

Answer- In myopia, or nearsightedness, the image is focused in front of the retina, causing distant objects to appear blurry. To correct this vision defect, a concave lens is used. This type of lens diverges light rays before they enter the eye, effectively shifting the image back onto the retina, thus restoring clear vision. Object distance (u) = infinity = ∞ Image distance (v) = – 80 cm Focal length = f According to the lens formula, NCERT Solutions for Class 10 Chapter 11 Image 1 A concave lens of power – 1.25 D is required by the individual to correct his defect.

7. Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.

Answer-

An individual with hypermetropia, or farsightedness, can see distant objects clearly but struggles to focus on nearby objects. This occurs because the eye lens focuses incoming light rays behind the retina. To correct this, a convex lens is used. The convex lens converges the light rays before they enter the eye, ensuring that the image is properly focused on the retina, thus allowing the person to see nearby objects more clearly. NCERT Solutions for Class 10 Chapter 11 Image 2 The convex lens creates a virtual image of a nearby object (N’ in the above figure) at the near point of vision (N) of the individual suffering from hypermetropia. The given individual will be able to clearly see the object kept at 25 cm (near point of the normal eye), if the image of the object is formed at his near point, which is given as 1 m. Object distance, u = – 25 cm Image distance, v = – 1 m = – 100 m Focal length, f Using the lens formula, NCERT Solutions for Class 10 Chapter 11 Image 3 A convex lens of power +3.0 D is required to correct the defect.

8. Why is a normal eye not able to see clearly the objects placed closer than 25 cm?

Answer- A normal eye struggles to see objects clearly if they are placed closer than 25 cm because the ciliary muscles, which adjust the eye lens's focal length, can only contract up to a certain limit. Beyond this limit, the eye lens cannot accommodate enough to focus on very close objects, resulting in blurred vision for those near distances.

9. What happens to the image distance in the eye when we increase the distance of an object from the eye?

Answer- As an object is moved farther from the eye, the image continues to form on the retina because the eye lens adjusts its shape. Specifically, the eye lens becomes thinner, and its focal length increases to compensate for the greater distance. This adjustment ensures that the incoming light rays are properly focused on the retina, allowing the eye to see distant objects clearly.

10. Why do stars twinkle?

Answer- The twinkling of stars is caused by the atmospheric refraction of starlight. As starlight enters Earth's atmosphere, it passes through layers of air with varying densities, causing it to bend continuously. This bending, due to the changing refractive index of the atmosphere, results in the star's light being refracted in different directions. This constant fluctuation in the light's path makes the star appear to twinkle from our perspective on Earth.

11. Explain why the planets do not twinkle.

Answer- Unlike stars, planets don’t twinkle. The key reason is their relative proximity compared to stars. Planets appear as small discs rather than pinpoints of light due to their closer distance. This means their light is spread over a larger area in the sky. As a result, the light from planets is less affected by atmospheric interference and doesn't experience the same level of diffraction as starlight. Consequently, planets usually shine steadily without the twinkling effect observed with stars.

12. Why does the Sun appear reddish early in the morning?

Answer- White light from the sun travels a longer path through the Earth's atmosphere during sunrise and sunset. As the light travels this greater distance, shorter wavelengths (blue and violet) scatter more due to the atmosphere's particles. This scattering leaves the longer wavelengths (red and orange) to dominate the light that reaches the observer. As a result, the sun appears reddish during these times. This phenomenon is why we often see beautiful red and orange hues in the sky during sunrise and sunset.

13. Why does the sky appear dark instead of blue to an astronaut?

Answer- In space, outside the Earth's atmosphere, the sky appears dark instead of blue because there is no atmosphere to scatter sunlight. On Earth, the atmosphere scatters shorter wavelengths of light (blue and violet), giving the sky its blue color. However, in the vacuum of space, this scattering does not occur. As a result, astronauts see a dark sky, even when the sun is shining brightly.

Check Out: CBSE Class 10 Sample Papers

How to Use NCERT Solutions for Class 10 Science Chapter 11?

Check How to Use NCERT Solutions for Class 10 Science Chapter 11 below:-

1. Start with Understanding the Chapter

Before jumping into the human eye and colourful world question answer, it’s important to know what the chapter actually explains. Class 10 Science Chapter 11 question answer becomes easier once you connect it with the theory from the textbook.

Read about the structure and function of the human eye.
Go through concepts like accommodation, near point, and far point.
Understand scattering of light and natural phenomena like the twinkling of stars.

2. Go Through the NCERT Questions One by One

The real benefit comes when you connect the theory with the human eye and the colourful world question answer given at the end of the chapter.

Try to solve each question by yourself first.
Compare your answers with the given solutions.
Notice how the solutions are written in clear exam-style language.

3. Focus on Numerical Problems

In the human eye and colourful world class 10 questions with answers, some problems involve the power of the lens, focal length, and lens formula.

Practise step-by-step calculations.
Remember units like dioptre and metre.
Revise the formula: P=1/f frequently.

4. Revise with Concept-Based Questions

Many human eye and colourful world question answer class 10 are based on concepts like refraction, dispersion, or atmospheric phenomena.

Revise why the sun appears red at sunrise and sunset.
Recall why planets do not twinkle.
Connect each answer with the scientific principle behind it.

5. Practice Writing Answers in Simple Language

Writing style matters in exams, so practising the class 10 science chapter 11 question answer in your own words helps you remember better.

Avoid long and confusing sentences.
Use diagrams wherever possible.
Write to-the-point answers just like in NCERT solutions.

Also Check: CBSE Class 10 Question Banks

Human Eye and Colourful World FAQs

Q1. What is the main concept of Class 10 Science Chapter 11 Human Eye and Colourful World?

This chapter explains how the human eye works, the role of the eye lens, accommodation, and common vision defects. It also covers natural phenomena like twinkling of stars, scattering of light, and the reddish appearance of the sun.

Q2. Why should I practise Human Eye and Colourful World question answer from NCERT?

Because the textbook questions cover every key topic. Practising them helps you prepare well for both theory and numerical parts of the exam.

Q3. What does the Human Eye and the Colourful World question answer teach about defects of vision?

It explains myopia (short-sightedness), hypermetropia (long-sightedness), and presbyopia, along with how corrective lenses are used to fix them.

Q4. Are there numerical problems in Human Eye and Colourful World question answer Class 10?

Yes, numericals include finding focal length and power of lenses used to correct vision defects. These are simple but important for exams.

Q5. What is the least distance of distinct vision discussed in this chapter?

For a normal human eye, the least distance of distinct vision is 25 cm. Objects closer than this appear blurred.

Recommended for you

See All