Real-world connection: Think of the eye like a camera — the cornea and lens focus light, the pupil works like the aperture ring (getting wider in dim light and smaller in bright light), and the retina is the sensor that captures the image. Just as a camera can be near-sighted or far-sighted depending on its lens setting, your eye can have the same problems — corrected with the right spectacle lens.
Topic 1: Parts of the Eye
Cornea is the clear front cover.
Iris gives our eye its colour.
Pupil is the small black hole.
Lens bends light onto the retina.
Retina sends signals to the brain.
Topic 2: How We See Things
Light enters the eye through cornea.
Pupil gets big in dark rooms.
Pupil gets small in bright light.
Lens bends light to form image.
Brain reads the image we see.
Topic 3: Power of Accommodation
Lens can change its own shape.
It gets thin for far away things.
It gets thick for nearby things.
This ability is called accommodation.
Ciliary muscles control the lens shape.
Topic 4: Myopia (Short Sight)
Nearby things look clear and sharp.
Far things look blurry and unclear.
The eyeball is too long here.
Image forms before the retina screen.
A concave lens fixes this problem.
Topic 5: Hypermetropia (Long Sight)
Far things look clear and sharp.
Nearby things look blurry and unclear.
The eyeball is too short here.
Image forms behind the retina screen.
A convex lens fixes this problem.
Topic 6: Presbyopia (Old Age Sight)
Ciliary muscles get weak with age.
Lens cannot change its shape well.
Both near and far look blurry.
A bifocal lens helps fix this.
It has two lens types in one.
Topic 7: Refraction Through a Prism
A prism is a triangle shaped glass.
White light goes into the prism.
Light bends and splits into colours.
We see a beautiful rainbow band.
This band is called a spectrum.
Topic 8: Dispersion of Light
White light has seven different colours.
A prism separates all these colours.
VIBGYOR is the colour order we see.
Violet bends the most of all.
Red bends the least of all.
Topic 9: Scattering of Light
Tiny particles in air scatter light.
Blue light scatters the most easily.
The sky looks blue because of this.
Tyndall effect shows the light path.
Dust makes light beams easy to see.
Topic 10: Why Sun Looks Red
At sunrise light travels very far.
Blue light scatters away on the way.
Only red light reaches our eyes.
The sunset sky also looks red.
This happens due to atmospheric refraction.
Section 2 – Easy Pictures
Figure 1: Parts of the Human Eye
Figure 2: Myopia and Its Correction
Figure 3: Hypermetropia and Its Correction
Figure 4: Dispersion of Light Through a Prism
Figure 5: Why the Sky Looks Blue
Section 3 – Worked Examples
Example 1: Finding the Right Lens
Question: A boy cannot see beyond 5 m. What lens does he need?
1
He sees near things but not far.
2
This means he has myopia.
3
In myopia, the eyeball is too long.
4
Image forms before the retina screen.
5
A concave lens will fix this.
Answer: He needs a concave lens.
Example 2: Power of a Lens
Question: A lens has focal length 50 cm. Find its power.
1
Focal length f = 50 cm.
2
Change cm to metres: f = 0.5 m.
3
Formula: P = 1 ÷ f.
4
P = 1 ÷ 0.5 = 2.
5
Power is written in dioptres (D).
Answer: Power of the lens = +2 D.
Example 3: Light Path Through a Prism
Question: How does light bend in a prism?
1
White light hits one side of prism.
2
Light bends when it enters the glass.
3
Different colours bend by different amounts.
4
Light bends again when it comes out.
5
We see a rainbow band of colours.
Answer: Light bends twice and splits into seven colours. The angle it turns is called the angle of deviation.
Section 4 – Cheat Sheet
Word
What It Means
Cornea
Clear front cover of the eye.
Iris
Coloured part that controls light entry.
Pupil
Black hole that lets light in.
Lens
Bends light to make a clear image.
Retina
Screen at the back of the eye.
Myopia
Cannot see far things clearly.
Hypermetropia
Cannot see near things clearly.
Presbyopia
Old age sight problem, both blur.
Dispersion
Splitting of white light into colours.
Spectrum
Band of seven colours from a prism.
Tyndall Effect
Light path seen through tiny particles.
Scattering
Light bouncing off tiny air particles.
Section 5 – Take-Home Handout
Part A: Fill in the Blanks
1. The clear front cover of the eye is called the __________.
2. The __________ controls how much light enters the eye.
3. The image forms on the __________ inside the eye.
4. A concave lens is used to fix __________.
5. The splitting of light into colours is called __________.
Part B: True or False
1. The pupil is the coloured part of the eye.
2. In myopia, far things look blurry.
3. A convex lens fixes hypermetropia.
4. Red light scatters the most in sky.
5. VIBGYOR has seven different colours.
Part C: Solve These Problems
1. A girl cannot see things beyond 3 m. What kind of lens does she need? Why?
2. A lens has focal length 25 cm. Find its power in dioptres.
3. Why does the sun look red at sunrise? Write three points.
Part D: Match the Columns
Column A
1. Myopia
2. Dispersion
3. Iris
4. Tyndall Effect
5. Presbyopia
Column B
a. Light path in dust
b. Eye colour
c. Bifocal lens
d. Concave lens
e. Prism and rainbow
Part E: Draw and Label
Draw a neat picture of the human eye. Label these parts: cornea, iris, pupil, lens, retina, optic nerve.
✅ Detailed Solutions – Section 5 Handout
Part A: Fill in the Blanks
1
The clear front cover of the eye is the cornea.
2
The iris controls how much light enters the eye (by changing pupil size).
3
The image forms on the retina inside the eye.
4
A concave lens is used to fix myopia (short-sightedness).
5
The splitting of light into colours is called dispersion.
Part B: True or False
1
False. The pupil is the black opening; the iris is the coloured part.
2
True. In myopia the eyeball is too long, so distant objects appear blurry.
3
True. A convex lens converges light so the image falls correctly on the retina.
4
False. Blue light scatters the most; red light scatters the least.