NCERT Class 8 Science Science: Chapter 13 — Light
This chapter, "Light," from NCERT Class 8 Science, explores the fundamental principles of light and vision. It begins by explaining that seeing objects is possible only when light enters our eyes, either emitted or reflected by the object. The chapter introduces the concept of reflection, explaining how polished surfaces like mirrors change the direction of light. Key terms like incident ray and reflected ray are defined. Activity 13.1 demonstrates the reflection of light using a comb and a mirror, leading to the discovery of the laws of reflection. The angle of incidence and angle of reflection are measured, establishing that they are equal. Activity 13.2 further investigates the nature of reflected rays by bending a paper strip, highlighting how light travels in straight lines. This chapter is crucial for understanding optics and visual perception in physics.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 8 |
| Subject | Science |
| Book | Science |
| Chapter | Chapter 13 — Light |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 3 minutes |
| Word count | 472 |
Learning outcomes
- Explain how we see objects.
- Define incident ray and reflected ray.
- Understand the role of polished surfaces in reflection.
- State and verify the laws of reflection.
- Recognize that light travels in straight lines.
Vocabulary
| Word | Meaning |
|---|---|
| Reflection | The bouncing back of light when it strikes a surface. |
| Incident ray | The ray of light that strikes a surface. |
| Reflected ray | The ray of light that comes back from the surface after reflection. |
| Normal | A line perpendicular to the reflecting surface at the point of incidence. |
| Angle of incidence | The angle between the normal and the incident ray. |
| Angle of reflection | The angle between the normal and the reflected ray. |
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Practice questions
- What is necessary for us to see an object? Answer: Light from the object must enter our eyes.
- Define the incident ray and the reflected ray. Answer: The incident ray is the light ray striking a surface, and the reflected ray is the light ray that bounces back from the surface.
- What is the relationship between the angle of incidence and the angle of reflection? Answer: The angle of incidence is always equal to the angle of reflection.
- What is the normal to a reflecting surface? Answer: The normal is a line drawn perpendicular to the reflecting surface at the point where the incident ray strikes.
Frequently asked questions
How do we see objects?
We see objects when light from them enters our eyes. This light can be emitted by the object or reflected by it.
What is the role of a mirror in reflection?
A mirror is a polished surface that reflects light, changing its direction.
What is the first law of reflection?
The first law of reflection states that the angle of incidence is equal to the angle of reflection.
What is the incident ray?
The incident ray is the ray of light that falls on a surface.
What is the reflected ray?
The reflected ray is the ray of light that bounces back from a surface after striking it.
What is the normal in the context of reflection?
The normal is a line perpendicular to the reflecting surface at the point where the light ray strikes.
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Topics covered
NCERT Class 8 Science — Science — Chapter 13 — Light. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.