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| Full chapter one shot revesion mind map |
👁️ Class 10 Physics — The Human Eye and The Colourful World FULL MASTER NOTES
CBSE Board 2026 | NCERT Based | Detailed Notes + Diagrams + PYQs + Tricks + Important Questions
📖 INTRODUCTION
The human eye is a natural optical instrument that helps us see objects around us.
This chapter explains:
- Structure of human eye
- Defects of vision
- Atmospheric refraction
- Scattering of light
- Rainbow formation
This chapter is very important for CBSE Board exams because:
- Ray diagrams are asked
- Numerical formulas come
- Defects of vision are frequently asked
🌟 HUMAN EYE ⭐ VERY IMPORTANT
Human eye helps us:
- See objects
- Identify colours
- Adjust focus automatically
🌟 HUMAN EYE DIAGRAM
 |
| Human eye diagram and function |
⭐
_________
.-' '-.
.' Cornea '.
/ \
| Aqueous |
| Humour |
| ____ |
| / Lens\ |
| | | |
| \_____/ |
| | |
| Retina |
\ /
'. Optic Nerve .'
'-._________.-'
🌟 PARTS OF HUMAN EYE
| Part | Function |
|---|---|
| Cornea | Refracts light |
| Iris | Controls pupil size |
| Pupil | Controls amount of light |
| Eye lens | Focuses light |
| Retina | Forms image |
| Optic nerve | Sends signals to brain |
🌟 FUNCTION OF IRIS ⭐
Iris controls size of pupil.
- Bright light → Pupil contracts
- Dim light → Pupil expands
🌟 RETINA ⭐
Sensitive screen where image forms.
Contains:
- Rod cells → Black & white vision
- Cone cells → Colour vision
🌟 POWER OF ACCOMMODATION ⭐ VERY IMPORTANT
Ability of eye lens to adjust focal length.
🌟 NEAR POINT AND FAR POINT
| Point | Distance |
|---|---|
| Near point | 25 cm |
| Far point | Infinity |
🌟 CATARACT ⭐
Condition in which eye lens becomes cloudy.
Treatment:
- Eye surgery
🌟 DEFECTS OF VISION ⭐ VERY IMPORTANT
1. MYOPIA (Short-sightedness)
Person:
- Can see nearby objects clearly
- Cannot see distant objects clearly
🌟 Cause of Myopia
- Eye lens too curved
- Eyeball elongated
🌟 CORRECTION OF MYOPIA
Corrected using:
- Concave lens
🌟 MYOPIA DIAGRAM
Distant Object → )( → Eye
Concave Lens
2. HYPERMETROPIA (Long-sightedness)
Person:
- Can see distant objects clearly
- Cannot see nearby objects clearly
🌟 Cause of Hypermetropia
- Eyeball too short
- Focal length too large
🌟 CORRECTION OF HYPERMETROPIA
Corrected using:
- Convex lens
🌟 HYPERMETROPIA DIAGRAM
Near Object → () → Eye
Convex Lens
3. PRESBYOPIA ⭐
Defect due to ageing.
Old people cannot see nearby objects clearly.
🌟 Cause
Weakening of ciliary muscles.
🌟 CORRECTION
- Bifocal lens
🌟 DIFFERENCE BETWEEN MYOPIA AND HYPERMETROPIA ⭐
| Myopia | Hypermetropia |
|---|---|
| Cannot see distant objects | Cannot see nearby objects |
| Corrected by concave lens | Corrected by convex lens |
| Image forms before retina | Image forms behind retina |
🌟 REFRACTION OF LIGHT THROUGH PRISM ⭐
Prism bends light due to refraction.
🌟 PRISM DIAGRAM
/\
/ \
White /____\ Spectrum
Light
🌟 DISPERSION OF LIGHT ⭐ VERY IMPORTANT
Splitting of white light into seven colours.
🌟 VIBGYOR
- Violet
- Indigo
- Blue
- Green
- Yellow
- Orange
- Red
🌟 DISPERSION DIAGRAM
White Light → Prism → VIBGYOR
🌟 RAINBOW FORMATION ⭐ VERY IMPORTANT
Rainbow forms due to:
- Refraction
- Dispersion
- Internal reflection
of sunlight by water droplets.
🌟 RAINBOW DIAGRAM
Sunlight → Water Droplet → Rainbow
🌟 ATMOSPHERIC REFRACTION ⭐
Refraction caused by atmosphere.
🌟 TWINKLING OF STARS ⭐
Stars twinkle due to atmospheric refraction.
🌟 WHY PLANETS DO NOT TWINKLE?
Planets are closer and appear as extended sources.
🌟 ADVANCED SUNRISE AND DELAYED SUNSET ⭐
Sun appears earlier due to atmospheric refraction.
🌟 SCATTERING OF LIGHT ⭐ VERY IMPORTANT
Spreading of light by particles.
🌟 Tyndall Effect
Scattering of light by colloidal particles.
🌟 WHY SKY APPEARS BLUE? ⭐
Blue colour scatters more due to shorter wavelength.
🌟 WHY SUN APPEARS RED AT SUNRISE/SUNSET?
Red colour scatters least due to longer wavelength.
🌟 SCATTERING DIAGRAM
Sunlight → Atmosphere → Scattered Blue Light
🌟 IMPORTANT FORMULA ⭐
Power of lens:
Where:
- P = Power
- f = Focal length
🌟 SI UNIT OF POWER
Dioptre (D)
🎯 MOST IMPORTANT BOARD QUESTIONS WITH ANSWERS
Q1. What is power of accommodation?
Answer:
Ability of eye lens to adjust focal length for seeing nearby and distant objects clearly is called power of accommodation.
Q2. What is myopia? How is it corrected?
Answer:
Myopia is defect in which nearby objects are seen clearly but distant objects are not visible clearly.
It is corrected using concave lens.
Q3. Why do stars twinkle?
Answer:
Stars twinkle due to atmospheric refraction of starlight.
Q4. Why does sky appear blue?
Answer:
Sky appears blue because blue colour scatters more due to shorter wavelength.
Q5. Why does sun appear reddish during sunrise and sunset?
Answer:
At sunrise and sunset sunlight travels longer distance. Most colours scatter except red. Therefore sun appears red.
🔥 IMPORTANT DIFFERENCES ⭐
Myopia vs Hypermetropia
| Myopia | Hypermetropia |
|---|---|
| Cannot see distant objects | Cannot see nearby objects |
| Concave lens used | Convex lens used |
| Image before retina | Image behind retina |
Stars vs Planets
| Stars | Planets |
|---|---|
| Twinkle | Do not twinkle |
| Very far away | Comparatively nearer |
🌟 IMPORTANT NCERT POINTS
- Near point = 25 cm
- Far point = Infinity
- Retina forms image
- Prism disperses light
- Blue colour scatters most
- Red colour scatters least
🧠 SUPER TRICKS
VIBGYOR Trick:
“VIBGYOR”
- Violet
- Indigo
- Blue
- Green
- Yellow
- Orange
- Red
Defects Correction:
- Myopia → Concave
- Hypermetropia → Convex
✍️ MOST IMPORTANT DIAGRAMS FOR BOARDS
- Human eye
- Myopia correction
- Hypermetropia correction
- Prism dispersion
- Rainbow formation
🎯 EXPECTED QUESTIONS FOR CBSE BOARD 2026
- Draw labelled diagram of human eye.
- Explain myopia and its correction.
- Explain hypermetropia and correction.
- What is atmospheric refraction?
- Why do stars twinkle?
- Explain rainbow formation.
- Why is sky blue?
- Explain dispersion of light by prism.
- If you want MCQ type question 100+ comment me .
