Welcome To My School Study
Do You Know
1. Reflection of Light
Reflection is the phenomenon in which light rays bounce back after striking a smooth and shiny surface.
How it happens:
When light falls on a mirror or polished surface, it returns into the same medium.
Important Points:
- Reflection follows certain laws
- Smooth surfaces produce clear reflection
- Rough surfaces scatter light in different directions
Examples:
- Seeing your face in a mirror
- Reflection of objects in still water
2. Angle of Incidence and Angle of Reflection
According to the law of reflection, the angle of incidence is always equal to the angle of reflection.
Definitions:
- Angle of incidence → angle between incoming ray and normal
- Angle of reflection → angle between reflected ray and normal
Law of Reflection:
Angle of incidence = Angle of reflection
Importance:
This law helps explain how mirrors form images.
Example:
If the angle of incidence is 30°, the angle of reflection will also be 30°.
3. Image Formed by a Plane Mirror
A plane mirror forms an image that is virtual and erect.
Characteristics of the image:
- Virtual → cannot be obtained on a screen
- Erect → upright image
- Same size as the object
- Laterally inverted (left-right reversed)
Understanding:
The reflected rays appear to come from behind the mirror, but they do not actually meet there.
Example:
Your image in a bathroom mirror.
4. Dispersion of Light
Dispersion is the process in which white light splits into seven different colours.
Reason for dispersion:
Different colours bend by different amounts when passing through a prism.
Seven colours formed:
- Violet
- Indigo
- Blue
- Green
- Yellow
- Orange
- Red
Example:
Rainbow formation after rain.
Importance:
Dispersion shows that white light is made up of many colours.
5. Iris (Control of Light in the Eye)
The iris is the coloured part of the eye that controls the amount of light entering the eye.
How it works:
- In bright light → iris makes pupil smaller
- In dim light → iris makes pupil larger
Function:
It protects the eye from too much light and helps in proper vision.
Related Parts:
- Pupil → opening through which light enters
- Retina → forms image
- Lens → focuses light
Example:
Your pupils become smaller in sunlight because the iris adjusts them.