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๐ฌ Think about it
Hold a steel plate in the Sun and a bright spot of light dances on a shaded wall. You did not move the Sun, yet the light changed direction. How? A shiny surface bounced it. Let us study reflection.
What is the reflection of light?
- A shiny surface or mirror changes the direction of light.
- This change of direction by a mirror is called reflection.
- Light still travels in straight lines before and after.
- Tilting the mirror moves the bright spot to a new place.
Example:
A steel plate in the Sun throws a bright spot of light onto a shaded wall, and tilting it moves the spot.
In this Activity, we will use a shiny plate in sunlight to redirect light onto a wall.
Materials needed
A shiny flat steel plate or a plane mirror (flat, not curved).
Procedure
1. Take the shiny plate or plane mirror outside.
2. Let sunlight fall on the shiny surface.
3. Try to redirect the light onto a wall where sunlight does not fall directly.
2. Let sunlight fall on the shiny surface.
3. Try to redirect the light onto a wall where sunlight does not fall directly.
Observation
A bright spot of light appears on the shaded wall.
Explanation
The shiny surface changed the direction of the light that fell on it. This change of direction by a mirror is called reflection.
โ Summary
- Sunlight fell on plate
- Light redirected to wall
- Bright spot appeared
- Mirror changed direction
In this Activity, we will send a thin beam of light onto a mirror and watch it change direction.
Materials needed
A plane mirror with stand, a torch, a comb, a sheet of white paper, and a strip of black paper.
Procedure
1. Use the black paper to close all openings of the comb except one, making a thin slit.
2. Spread white paper on a table and hold the comb upright on it.
3. Shine the torch on the slit to get a thin beam of light on the paper.
4. Place the mirror in the path of the beam, keeping the comb steady.
5. Observe how the beam changes.
2. Spread white paper on a table and hold the comb upright on it.
3. Shine the torch on the slit to get a thin beam of light on the paper.
4. Place the mirror in the path of the beam, keeping the comb steady.
5. Observe how the beam changes.
Observation
The path of the light beam changes after it falls on the mirror.
Explanation
The mirror reflects the light, so the beam bounces off in a new direction. Reflection happens at the mirror.
โ Summary
- Thin beam made with comb
- Mirror placed in path
- Beam changed direction
- Reflection at the mirror
Important Points
- A mirror changes the direction of light that falls on it.
- This change of direction is called reflection.
- Light still travels straight between bounces.
โ Test Yourself
-
What is reflection of light?
View Answer
The change in the direction of light by a mirror. -
What kind of surface reflects light well?
View Answer
A shiny surface, like a plane mirror or steel plate. -
What is a plane mirror?
View Answer
A mirror that is flat and not curved. -
Where does reflection happen in Activity 11.6?
View Answer
At the mirror. -
Does light stop being straight after reflection?
View Answer
No, it travels straight in its new direction.
Important Definitions
- Reflection of light — the change in the direction of light when it falls on a mirror or shiny surface.
- Plane mirror — a mirror that is flat and not curved.
