The Human Eye and the Colourful World is Chapter 10 in CBSE Class 10 Science. It covers how the human eye works, common defects of vision and their correction, refraction through a prism, dispersion of white light, atmospheric refraction, and scattering of light.
Important Questions Class 10 Science Chapter 10 on this page cover MCQs, short answer, long answer, numericals, and topic-wise questions built around the NCERT 2026-27 syllabus.
Important Questions Class 10 Science Chapter 10
Q.
Which one of the following materials cannot be used to make a lens?
(a) Water
(b) Glass
(c) Plastic
(d) Clay
Q.
An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.
Q.
Find the focal length of a lens of power – 2.0 D. What type of lens is this?
Q.
An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focussed image can be obtained? Find the size and the nature of the image.
Q.
An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position of the image, its nature
and size.
Q.
The magnification produced by a plane mirror is +1. What does this mean?
Q.
An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image.
Q.
A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.
Q.
One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your
observations.
Q.
The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object?
(a) Between the principle focus and the centre of curvature
(b) At the centre of curvature
(c) Beyond the centre of curvature
(d) Between the pole of the mirror and its principle focus.
Q.
Name the type of mirror used in the following situations.
(a) Headlights of a car
(b) Side/rear-view mirror of a vehicle.
(c) Solar furnace
Support your answer with reason.
Q.
We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.
Q.
Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
(a) A convex lens of focal length 50 cm
(b) A concave lens of focal length of 50 cm
(c) A convex lens of focal length of 5 cm
(d) A concave lens of focal length 5 cm
Q.
No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be-
(a) only plane.
(b) only concave.
(c) only convex.
(d) either plane or convex.
Q.
A spherical mirror and a thin spherical lens have each a focal length of –15 cm. The mirror and the lens are likely to be
(a) both concave.
(b) both convex.
(c) the mirror is concave and the lens is convex.
(d) the mirror is convex and the lens is concave.
Q.
Where should an object be placed in front of a convex lens to get a real image of the size of the object?
(a) At the principle focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principle focus.
Q.
A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?
This chapter carries marks across every question format in CBSE 2026 papers. A student who can draw and label a myopic eye correction diagram, write the power formula, and explain why stars twinkle will handle questions from all three sections of the board paper. All questions and answers are available section by section below.
Key Takeaways
| Detail |
Info |
| Chapter |
The Human Eye and the Colourful World |
| Class |
10 |
| Subject |
Science |
| Board |
CBSE 2026-27 |
| Question Types |
MCQ, short answer, long answer, numericals |
| Answers Included |
Yes |
| Diagrams Covered |
Yes: myopia, hypermetropia, prism dispersion |
Introduction to The Human Eye and the Colourful World
The human eye focuses light onto the retina by adjusting the shape of its crystalline lens. When this adjustment fails or the eyeball dimensions change, vision defects result. Three defects: myopia, hypermetropia, and presbyopia appear in almost every board exam.
Beyond the eye itself, this chapter explains why white light splits into seven colours in a prism, why stars twinkle while planets do not, why the sky is blue, and why the Sun appears red at sunrise. Each of these is a standing exam topic.
For students targeting 90+ marks in CBSE 2026, this chapter rewards students who practise light extra questions class 10 because the variety of question types here is wider than most other chapters.
Important Topics in Class 10 Science Chapter 10
Every board question from this chapter maps to one of these seven topics. Know them before starting practice.
The Human Eye: structure, parts, and functions. Power of Accommodation. Defects of Vision: myopia, hypermetropia, presbyopia. Refraction of Light Through a Prism. Dispersion of White Light and Rainbow Formation. Atmospheric Refraction: twinkling of stars, advance sunrise. Scattering of Light: Tyndall effect, blue sky, red danger signals.
Class 10 Science Chapter 10 MCQs with Answers
These light important questions class 10 MCQs cover all seven topics. Each answer includes a one-line explanation to build understanding.
Q1. The human eye can focus on objects at different distances because of: (a) Presbyopia (b) Accommodation (c) Near-sightedness (d) Far-sightedness (b) Accommodation. Ciliary muscles adjust the focal length of the eye lens to focus at different distances.
Q2. The human eye forms the image of an object at its: (a) Cornea (b) Iris (c) Pupil (d) Retina (d) Retina. The retina is the light-sensitive screen where the eye lens forms a real and inverted image.
Q3. The least distance of distinct vision for a young adult with normal vision is: (a) 25 m (b) 2.5 cm (c) 25 cm (d) 2.5 m (c) 25 cm. Objects held closer than 25 cm cannot be seen clearly without strain.
Q4. The change in focal length of an eye lens is caused by the action of the: (a) Pupil (b) Retina (c) Ciliary muscles (d) Iris (c) Ciliary muscles. Ciliary muscles contract or relax to change the shape and focal length of the crystalline lens.
Q5. When a person is myopic, they can clearly see: (a) Both nearby and far-off objects (b) Only nearby objects (c) Only far-off objects (d) Neither (b) Only nearby objects. In myopia, the image of distant objects forms in front of the retina.
Q6. The defect of myopia can be corrected by using: (a) Concave lens (b) Convex lens (c) Either (d) Bifocal lens (a) Concave lens. A concave lens diverges the light rays so the image shifts back onto the retina.
Q7. The colour scattered the least by fine particles in the atmosphere is: (a) Violet (b) Blue (c) Yellow (d) Red (d) Red. Red has the longest wavelength and is scattered least, which is why danger signals use red light.
Q8. The focal length of the eye lens increases when the ciliary muscles: (a) Are relaxed and lens becomes thinner (b) Contract and lens becomes thicker (c) Are relaxed and lens becomes thicker (d) Contract and lens becomes thinner (a) Are relaxed and lens becomes thinner. Relaxed ciliary muscles flatten the lens, increasing focal length for distant vision.
Q9. Which part of the human eye determines eye colour? (a) Cornea (b) Iris (c) Pupil (d) Retina (b) Iris. Its pigmentation determines eye colour.
Q10. The twinkling of stars is due to: (a) Reflection of starlight (b) Dispersion of starlight (c) Atmospheric refraction of starlight (d) Scattering of starlight (c) Atmospheric refraction of starlight. Continuous refraction through atmospheric layers causes the flickering effect.
Q11. Planets do not twinkle because they: (a) Are point sources (b) Are extended sources (c) Are very far from Earth (d) Emit their own light (b) Are extended sources. Planets are close enough to appear as extended sources; light variations average out.
Q12. Which colour of light deviates the most when passing through a glass prism? (a) Red (b) Green (c) Yellow (d) Violet (d) Violet. Violet has the shortest wavelength and bends the most during refraction.
Q13. A rainbow is always formed in a direction: (a) Towards the Sun (b) Opposite to the Sun (c) At 90 degrees (d) Above the Sun (b) Opposite to the Sun. Sunlight refracts, reflects internally, and refracts again in raindrops, directing colours away from the Sun.
Q14. The sky would appear dark if: (a) The Sun were closer (b) Earth had no atmosphere (c) The Moon were absent (d) Stars were brighter (b) Earth had no atmosphere. Without atmospheric particles, no scattering occurs and the sky appears black.
Q15. The splitting of white light into its component colours is called: (a) Reflection (b) Refraction (c) Dispersion (d) Scattering (c) Dispersion. Different colours have different wavelengths and bend at different angles in a prism.
Q16. Hypermetropia is corrected using a: (a) Concave lens (b) Convex lens (c) Cylindrical lens (d) Bifocal lens (b) Convex lens. A convex lens converges the light rays so the image shifts forward onto the retina.
Q17. The Sun appears reddish at sunrise because: (b) Blue light is scattered away and red reaches us. Sunlight travels through thick atmosphere at sunrise, scattering shorter wavelengths.
Q18. Which part of the human eye controls the amount of light entering it? (a) Cornea (b) Lens (c) Pupil (d) Retina (c) Pupil. The pupil size is controlled by the iris. It contracts in bright light and expands in dim light.
Q19. The power of a lens is expressed in: (a) Metres (b) Centimetres (c) Dioptres (d) Hertz (c) Dioptres. Power P = 1/f where f is in metres.
Q20. Cataract is caused by: (a) Elongation of the eyeball (b) Weakening of ciliary muscles (c) The crystalline lens becoming milky and cloudy (d) Damage to the retina (c) The crystalline lens becoming milky and cloudy. Cataract is treated through surgery.
Q21. The Tyndall effect is observed when: (a) Light reflects off a mirror (b) Light passes through a colloidal solution (c) Light refracts through a prism (d) Light scatters off a flat surface (b) Light passes through a colloidal solution. Fine colloidal particles scatter the light beam, making its path visible.
Q22. The optic nerve carries signals from the retina to the: (a) Iris (b) Cornea (c) Ciliary muscles (d) Brain (d) Brain. The brain interprets electrical signals from the retina and processes visual information.
Human Eye and Power of Accommodation: Short Answer Questions
The structure of the human eye and accommodation form the base of this chapter. These class 10 light important questions appear as 1-mark and 2-mark questions in board exams regularly.
Q1. What is the least distance of distinct vision for a normal human eye? 25 cm. Objects held closer than this cannot be seen clearly without strain.
Q2. What is the far point of a normal human eye? Infinity. A normal eye sees objects clearly from 25 cm to infinity.
Q3. Define power of accommodation. Power of accommodation is the ability of the eye lens to adjust its focal length to focus on objects at different distances. The ciliary muscles control this process.
Q4. What happens to the focal length of the eye lens when you look at a nearby object? The ciliary muscles contract. The eye lens becomes thicker. The focal length decreases to bring the image onto the retina.
Q5. What is cataract? Cataract is a condition where the crystalline lens becomes milky and cloudy with age. It causes partial or complete loss of vision and requires surgical correction.
Q6. Which part of the human eye provides most of the refraction for entering light rays? The cornea provides most of the refraction. The crystalline lens provides only fine focal length adjustment.
Q7. What is the function of the iris and pupil? The iris controls the size of the pupil. The pupil regulates the amount of light entering the eye. In bright light the pupil contracts; in dim light it expands.
Q8. Where does the human eye form the image of an object? The eye lens forms a real and inverted image on the retina. The retina converts this into electrical signals sent to the brain via the optic nerve.
Q9. What is the role of ciliary muscles? Ciliary muscles control the shape of the crystalline lens. They contract for near vision (thicker lens, shorter focal length) and relax for distant vision (thinner lens, longer focal length).
Q10. Why is a normal eye not able to see objects placed closer than 25 cm? The power of accommodation exhausts at 25 cm. Ciliary muscles cannot contract further. The eye cannot reduce focal length enough to focus on closer objects.
Q11. What is the nature of the image formed on the retina? The image on the retina is real and inverted. The brain interprets and corrects this so we perceive objects as upright.
Q12. Which part of the human eye conveys electrical signals to the brain? The optic nerve carries electrical signals from the light-sensitive cells of the retina to the brain.
Q13. What happens to the pupil size when light is very bright? The iris makes the pupil smaller to limit the amount of light entering the eye and prevent retinal damage.
Q14. Why are we unable to see clearly when we come out of a dark room into bright light? In a dark room, the iris expands the pupil to allow more light in. When we step into bright light suddenly, a large amount of light enters at once, causing temporary glare until the pupil adjusts.
Q15. Name the fluid that fills the space between the cornea and the lens. Aqueous humour fills the space between the cornea and the crystalline lens.
Defects of Vision and Their Correction: Short Answer Questions
Defects of vision are the most tested topic in this chapter. CBSE 2026 sets 3-mark and 5-mark questions asking for causes, diagrams, and correction methods. These important questions of light class 10 cover every defect type.
Q1. What is myopia? State its causes and correction. Myopia is near-sightedness. The person sees nearby objects clearly but not distant ones. The image of a distant object forms in front of the retina. Causes: excessive curvature of the eye lens or elongation of the eyeball. Correction: a concave lens of suitable power.
Q2. What is hypermetropia? State its causes and correction. Hypermetropia is far-sightedness. The image of a nearby object forms behind the retina. Causes: the focal length of the eye lens is too long, or the eyeball is too small. Correction: a convex lens of suitable power.
Q3. What is presbyopia? State its causes and correction. Presbyopia is an age-related defect where the person cannot see nearby objects clearly. Causes: weakening of ciliary muscles and reduced flexibility of the eye lens. Correction: bifocal lenses with concave upper half for distance and convex lower half for near vision.
Q4. A student has difficulty reading the blackboard while sitting in the last row. What defect does the child have? How is it corrected? The child has myopia. A concave lens of suitable power corrects this.
Q5. Name one defect of vision that cannot be corrected by spectacle lenses. Cataract cannot be corrected by any spectacle lens. It requires surgery.
Q6. What type of lens is used for correcting hypermetropia? A convex lens is used. It converges the light rays so the image shifts forward onto the retina.
Q7. What is the near point of a person with hypermetropia? The near point of a hypermetropic person is farther than the normal 25 cm. Such a person must hold reading material well beyond 25 cm to see it clearly.
Q8. A person with a myopic eye cannot see objects beyond 1.2 m. What type of lens corrects this? A concave lens with focal length 1.2 m corrects this. The lens forms the image of distant objects at 1.2 m so the eye can see them clearly.
Q9. What is the difference between the far point of a myopic eye and a normal eye? For a normal eye, the far point is infinity. For a myopic eye, the far point is closer than infinity, often just a few metres away.
Q10. Can a person suffer from both myopia and hypermetropia? Yes. Such a person uses bifocal lenses. The upper portion is a concave lens for distant vision and the lower portion is a convex lens for near vision.
Q11. Why does the power of accommodation decrease with age? With age, ciliary muscles weaken and the eye lens loses flexibility. The lens cannot change its curvature as effectively, so the range of clear clear vision narrows.
Refraction Through a Prism and Dispersion: Short Answer Questions
Students often mix up dispersion and scattering in exams. These light reflection and refraction important questions keep the two concepts separate and exam-ready.
Q1. What is dispersion of light? Dispersion is the splitting of white light into its component colours when passing through a prism. The seven colours are Violet, Indigo, Blue, Green, Yellow, Orange, Red: VIBGYOR.
Q2. Which colour deviates the most through a prism? Which deviates the least? Violet deviates the most. Red deviates the least. Different wavelengths travel at different speeds in glass and bend at different angles.
Q3. What is a spectrum? A spectrum is a band of coloured components of a light beam, obtained when white light splits into its seven constituent colours.
Q4. Who first used a glass prism to obtain the spectrum of sunlight? Sir Isaac Newton first used a glass prism to obtain the spectrum of sunlight.
Q5. Why does a rainbow always form opposite to the Sun? Water droplets act as small prisms. They refract, internally reflect, and refract sunlight again. This directs the dispersed colours away from the Sun and toward the observer.
Q6. What is the angle of deviation in a prism? The angle of deviation is the angle between the direction of the incident ray and the emergent ray after passing through the prism.
Q7. What is the sequence of colours in the visible spectrum? Violet, Indigo, Blue, Green, Yellow, Orange, Red: VIBGYOR. Violet has the shortest wavelength; red has the longest.
Q8. What happens when two identical prisms are placed in inverted positions relative to each other? The second prism recombines the dispersed colours from the first prism. White light emerges from the other side of the second prism.
Q9. Why do different colours of light bend at different angles in a prism? Different colours have different wavelengths. They travel through glass at different speeds. Glass has a different refractive index for each colour, so each colour bends at a different angle.
For formula-based revision, visit Snell's Law Formula.
Atmospheric Refraction: Short Answer Questions
Atmospheric refraction questions carry 2-3 marks in CBSE 2026 papers. These light chapter class 10 important questions include the standing twinkling stars versus non-twinkling planets distinction.
Q1. What is atmospheric refraction? Atmospheric refraction is the refraction of light by the Earth's atmosphere. It happens because the atmosphere has layers of different optical densities. Light bends continuously as it passes through these layers.
Q2. Why do stars twinkle? Stars are very far away and act as point sources. Continuous atmospheric refraction shifts the apparent position of the star. The amount of light entering the eye keeps changing, producing the twinkling effect.
Q3. Why do planets not twinkle? Planets are closer and act as extended sources. Light variations from the many point sources that make up a planet's image average out to zero. The twinkling effect is cancelled.
Q4. Why does the Sun appear about 2 minutes before actual sunrise? Atmospheric refraction bends sunlight towards the normal as it enters denser atmospheric layers near the surface. The Sun appears above the horizon before it has actually crossed it.
Q5. Why do objects near a fire appear to waver? The air above a fire is hotter and less dense than cooler air above it. This creates layers of different refractive indices. As these layers keep shifting, the apparent position of objects seen through this hot air fluctuates continuously.
Q6. What causes the apparent flattening of the Sun's disc at sunrise and sunset? Atmospheric refraction bends light from the lower part of the Sun's disc more than light from the upper part. This unequal bending compresses the vertical dimension, making the Sun appear flattened.
Q7. Would stars twinkle if observed from the Moon? No. The Moon has no atmosphere. Without atmospheric layers, there is no refraction. Stars would appear as steady point sources of light.
Scattering of Light: Short Answer Questions
Scattering questions are straightforward but students often confuse causes. These extra questions for class 10 science on scattering lead with the direct answer for featured-snippet extraction.
Q1. Why does the sky appear blue? Blue light has a shorter wavelength. Fine particles in the atmosphere scatter shorter wavelengths more strongly. Blue light scatters in all directions and reaches our eyes.
Q2. Why does the sky appear dark to an astronaut? Outer space has no atmosphere. Without atmospheric particles, no scattering of sunlight occurs. With no scattered light reaching the eyes, the sky looks black.
Q3. Why are danger signals coloured red? Red has the longest wavelength in the visible spectrum. It scatters the least in fog, smoke, and dust. Red signals remain visible at greater distances in all weather conditions.
Q4. What is the Tyndall effect? The Tyndall effect is the scattering of light by fine colloidal particles, making the path of the light beam visible. It is seen when a beam of sunlight enters a smoke-filled room or passes through a canopy of dense forest.
Q5. Why does the Sun appear reddish at sunrise and sunset? At sunrise and sunset, sunlight travels through a greater thickness of atmosphere. Shorter wavelengths scatter away. Only longer wavelengths: red and orange, reach our eyes.
Q6. Why does the colour of the sky depend on the size of scattering particles? Very fine particles scatter mainly blue light. Larger particles scatter light of longer wavelengths. If particles are large enough, scattered light appears white, which is why clouds appear white.
Q7. What would happen to the colour of the sky if Earth had no atmosphere? The sky would appear completely dark or black. Without an atmosphere there would be no particles to scatter sunlight.
Q8. Can visible light be scattered by atoms and molecules in the Earth's atmosphere? Yes. Air molecules are smaller than the wavelength of visible light but still scatter shorter wavelengths effectively. This is the primary cause of the blue sky.
Q9. State one effect produced by the scattering of light by the atmosphere. The Tyndall effect: the path of a light beam becomes visible when it passes through the atmosphere or a colloidal medium due to scattering.
Q10. Why does light from the deep sea appear blue? Water preferentially scatters shorter wavelengths of light. In deep water, blue light is scattered back to the observer's eyes while other colours are absorbed.
Class 10 Science Chapter 10 Numericals with Solutions
These light extra questions class 10 include the numerical types most commonly set in CBSE board exams. The core formula is P = 1/f with f in metres.
Q1. The far point of a myopic person is 80 cm. Find the nature and power of the corrective lens. f = -80 cm = -0.8 m. P = 1/(-0.8) = -1.25 D. Nature: concave lens.
Q2. A person needs -5.5 D for distant vision and +1.5 D for near vision. Find the focal length of each lens. Distant: f = 1/(-5.5) = -0.182 m = -18.2 cm. Near: f = 1/(1.5) = 0.667 m = +66.7 cm.
Q3. The near point of a hypermetropic eye is 1 m. Find the power of the corrective lens. (Normal near point = 25 cm.) v = -100 cm, u = -25 cm. 1/f = 1/v - 1/u = 1/(-100) - 1/(-25) = -1/100 + 4/100 = 3/100. f = 100/3 cm = 1/3 m. P = +3.0 D. Nature: convex lens.
Q4. A person wears eyeglasses of focal length -70 cm. What is the far point? f = -70 cm, u = -infinity. 1/v = 1/f + 1/u = 1/(-70) + 0. v = -70 cm. Far point = 70 cm in front of the eye.
Q5. A person uses lenses of power -5.5 D for distant vision and +1.5 D for near vision. Find the focal length for near vision. f = 1/P = 1/1.5 = +0.667 m = +66.7 cm.
Q6. A certain person has a minimum distance of distinct vision of 150 cm. They wish to read at 25 cm. What focal length glass should they use? v = -150 cm, u = -25 cm. 1/f = 1/(-150) - 1/(-25) = -1/150 + 6/150 = 5/150 = 1/30. f = +30 cm. Nature: convex lens. The eye defect is hypermetropia.
Q7. A myopic person cannot see objects beyond 1.2 m. What power lens corrects this? f = -1.2 m. P = 1/(-1.2) = -0.83 D. Nature: concave lens.
Important Definitions and Diagram-Based Questions
These definition and diagram questions appear in every CBSE 2026 exam. Memorise definitions exactly and practise diagrams with full labels.
Definitions to memorise:
Accommodation: the ability of the eye lens to adjust its focal length to see objects at different distances. Near point: the minimum distance at which the eye sees objects clearly without strain — 25 cm for a normal eye. Far point: the farthest distance at which the eye sees objects clearly — infinity for a normal eye. Dispersion: the splitting of white light into its component colours. Atmospheric refraction: refraction of light by the Earth's atmosphere due to layers of different optical densities. Tyndall effect: scattering of light by colloidal particles, making the beam's path visible. Spectrum: a band of coloured components of a light beam — VIBGYOR.
Diagrams to draw in exams:
Structure of the human eye: label cornea, iris, pupil, crystalline lens, retina, optic nerve, ciliary muscles, vitreous humour, aqueous humour. Myopic eye and its correction with a concave lens. Hypermetropic eye and its correction with a convex lens. Dispersion of white light through a glass prism showing VIBGYOR. Rainbow formation showing refraction, internal reflection, and refraction again inside a raindrop.