NCERT Class 10 Science Science: Chapter 10 — The Human Eye and the Colourful World
This chapter, "The Human Eye and the Colourful World," from NCERT Class 10 Science, delves into the functioning of the human eye as a light-sensitive organ. It explains how the eye, akin to a camera, uses a lens system to form an image on the retina. Key components like the cornea, iris, pupil, and retina are described, along with the role of the optic nerves in transmitting signals to the brain. The chapter details the eye's power of accommodation, explaining how the ciliary muscles adjust the lens's focal length to focus on objects at varying distances, defining the near point (least distance of distinct vision) and far point. It also introduces common refractive defects like myopia, hypermetropia, and presbyopia, and briefly mentions cataract. This chapter is crucial for understanding vision and optical phenomena for CBSE students.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 10 |
| Subject | Science |
| Book | Science |
| Chapter | Chapter 10 — The Human Eye and the Colourful World |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 5 minutes |
| Word count | 806 |
Learning outcomes
- Describe the structure and function of the human eye.
- Explain the process of image formation on the retina.
- Define and explain the power of accommodation.
- Identify the near point and far point of the human eye.
- Recognize common refractive defects of vision and their causes.
Vocabulary
| Word | Meaning |
|---|---|
| Retina | The light-sensitive screen at the back of the eye where images are formed. |
| Cornea | The transparent outer layer at the front of the eye that refracts light. |
| Iris | A dark muscular diaphragm that controls the size of the pupil. |
| Pupil | The opening in the center of the iris that regulates the amount of light entering the eye. |
| Accommodation | The ability of the eye lens to adjust its focal length to focus on objects at different distances. |
| Least distance of distinct vision | The minimum distance at which objects can be seen clearly without strain (approx. 25 cm for a normal eye). |
| Far point | The farthest point up to which the eye can see objects clearly (infinity for a normal eye). |
| Cataract | A condition where the crystalline lens of the eye becomes milky and cloudy, causing vision loss. |
| Myopia | Near-sightedness; the defect where a person can see nearby objects clearly but not distant ones. |
| Hypermetropia | Far-sightedness; the defect where a person can see distant objects clearly but not nearby ones. |
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Practice questions
- What is the function of the iris and the pupil in the human eye? Answer: The iris controls the size of the pupil, and the pupil regulates the amount of light entering the eye.
- Explain the power of accommodation of the eye. Answer: It is the ability of the eye lens to adjust its focal length, by changing its curvature using ciliary muscles, to focus on objects at different distances.
- What is the least distance of distinct vision for a normal human eye? Answer: The least distance of distinct vision for a normal human eye is about 25 cm.
- Name the three common refractive defects of vision. Answer: The three common refractive defects of vision are myopia (near-sightedness), hypermetropia (far-sightedness), and presbyopia.
- What causes the condition known as cataract? Answer: Cataract is caused when the crystalline lens of people at old age becomes milky and cloudy.
Frequently asked questions
What is the primary function of the human eye?
The human eye enables us to see the world around us and perceive colors.
How does the human eye form an image?
The eye lens forms an inverted, real image of an object on the light-sensitive retina.
What is accommodation in the context of the human eye?
Accommodation is the eye's ability to change the focal length of its lens to focus on objects at varying distances.
What is the near point of a normal eye?
The near point is the minimum distance at which an object can be seen distinctly without strain, which is about 25 cm for a normal young adult eye.
What is the far point of a normal eye?
The far point is the farthest distance at which an object can be seen clearly. For a normal eye, this is infinity.
What are the main refractive defects of vision?
The main refractive defects are myopia (near-sightedness), hypermetropia (far-sightedness), and presbyopia.
What is cataract and how can it be treated?
Cataract is a condition where the eye lens becomes cloudy. It can often be treated with cataract surgery.
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NCERT Class 10 Science — Science — Chapter 10 — The Human Eye and the Colourful World. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.