Light Class 8 Science Chapter 16 : Light
Light Class 8 Science Chapter 16 Light notes, MCQs, question answers, human eye, reflection, defects of vision explained simply for CBSE students.
Table of Contents
📝 NOTES
🔹 1. What is Light?
- Light is a form of energy that enables us to see objects.
- Objects are visible when light from them enters our eyes.
🔹 2. Laws of Reflection
Reflection of light follows two laws:
- Angle of incidence = Angle of reflection
- The incident ray, reflected ray, and normal lie in the same plane
🔹 3. Regular and Diffused Reflection
| Regular Reflection | Diffused Reflection |
|---|---|
| Occurs on smooth surfaces | Occurs on rough surfaces |
| Forms clear image | Does not form clear image |
| Example: Mirror | Example: Wall |
🔹 4. Multiple Reflection
- When light reflects more than once, it is called multiple reflection.
- Used in:
- Periscope
- Kaleidoscope
🔹 5. Human Eye
The human eye is a natural optical instrument.
Main parts of the eye:
- Cornea – Protects the eye
- Iris – Controls amount of light
- Pupil – Opening through which light enters
- Lens – Focuses light on retina
- Retina – Forms image
- Optic nerve – Sends image to brain
🔹 6. Defects of Vision
a) Myopia (Near-sightedness)
- Can see nearby objects clearly
- Distant objects appear blurred
- Corrected using concave lens
b) Hypermetropia (Far-sightedness)
- Can see distant objects clearly
- Nearby objects appear blurred
- Corrected using convex lens
🔹 7. Dispersion of Light
- Splitting of white light into seven colours is called dispersion.
- Example: Rainbow
VIBGYOR colours:
Violet, Indigo, Blue, Green, Yellow, Orange, Red
🔹 8. Scattering of Light
- Scattering causes:
- Blue colour of sky
- Red colour of sunrise and sunset
🔹 9. Care of Eyes
- Read with proper light
- Eat vitamin-A rich food (carrot, spinach)
- Do not rub eyes
- Get eyes checked regularly
❓ Light Class 8 Science Chapter 16 QUESTION & ANSWERS
🔹 Very Short Answer (1 Mark)
Q1. What is reflection of light?
Ans: Bouncing back of light from a surface is called reflection.
Q2. Name the part of eye where image is formed.
Ans: Retina.
Q3. Which lens is used to correct myopia?
Ans: Concave lens.
🔹 Short Answer (2–3 Marks)
Q1. State the laws of reflection.
Ans:
- Angle of incidence equals angle of reflection.
- Incident ray, reflected ray, and normal lie in the same plane.
Q2. What is diffused reflection?
Ans: Reflection from rough surfaces that scatters light in many directions is called diffused reflection.
Q3. What is dispersion of light?
Ans: Splitting of white light into seven colours is called dispersion.
🔹 Long Answer (5 Marks)
Q1. Explain the structure of the human eye.
Ans:
The human eye consists of cornea, iris, pupil, lens, retina, and optic nerve. Light enters through the cornea, amount of light is controlled by iris, image is focused by the lens on the retina, and signals are sent to the brain through optic nerve.
Q2. Explain defects of vision and their correction.
Ans:
Myopia is corrected using concave lens and hypermetropia is corrected using convex lens. These lenses help focus light properly on the retina.
✅ Light Class 8 Science Chapter 16 MCQs – Chapter 16: Light
Choose the correct option
1. Angle of incidence is equal to:
A. Angle of refraction
B. Angle of reflection
C. Angle of dispersion
D. Angle of deviation
✅ Answer: B
2. Which surface gives regular reflection?
A. Wall
B. Paper
C. Mirror
D. Wood
✅ Answer: C
3. Image is formed on which part of the eye?
A. Cornea
B. Lens
C. Retina
D. Iris
✅ Answer: C
4. Myopia can be corrected using:
A. Convex lens
B. Concave lens
C. Plane mirror
D. Prism
✅ Answer: B
5. Splitting of white light is called:
A. Reflection
B. Refraction
C. Dispersion
D. Scattering
✅ Answer: C
6. Which colour bends the least in prism?
A. Violet
B. Indigo
C. Blue
D. Red
✅ Answer: D
7. Which instrument uses multiple reflection?
A. Microscope
B. Telescope
C. Periscope
D. Camera
✅ Answer: C
8. Blue colour of sky is due to:
A. Reflection
B. Refraction
C. Dispersion
D. Scattering
✅ Answer: D
9. Vitamin required for good eyesight is:
A. Vitamin B
B. Vitamin C
C. Vitamin D
D. Vitamin A
✅ Answer: D
10. Which part controls amount of light entering the eye?
A. Retina
B. Iris
C. Lens
D. Cornea
✅ Answer: B