Refraction Of Light
Chapter Name : Light-Reflection And Refraction |
Sub Topic Code : 101_10_10_03_04 |
Topic Name : Refraction Of Light |
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Sub Topic Name : Refraction By Spherical Lenses |
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Introduction
Like mirrors reflect the light, similarly lenses refract the light. i.e. they bend the light falling on them.
Pre-Requisites:
Introduction about refraction of light and laws of refraction.
Activity:
Take a magnifying glass and use it to focus the sun light on to a paper.
Real Life Question:
“Why we use lenses to correct the vision of an eye?” “Which type of lens is used in the making of binoculars?”
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Double convex lens | This lens has both of its surfaces spherical and curved outwards. |
| Optical center | The center point of the lens is called optical center. |
| Diverging lenses | Those lenses which diverge the rays falling on it. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Binoculars | It contains two lenses. Use it to see the objects near and more clear. |
Real life uses :
In camera, binoculars, telescopes, projectors, microscopes, sunglass lenses etc.
Places to visit :
Your physics lab is having lenses; also you can go to the optical showroom to see various kinds of lenses, a planetarium where you can observe the telescopes.
Practical examples around us
| Examples | Explainations |
|---|---|
| Spectacles | The glasses we use to wear to correct our vision is made up of lenses. |
| Camera | Camera uses the lens to focus on the object. |
What you learn in Theory:
Convex lens bend the light towards the principal axis and concave lens bend the light away from the principal axis. Light ray falling parallel to the lens passes through the focus after refraction.
What you learn in Practice:
Lenses refract light falling on it. That’s why it is used in various optical instruments. Using these lenses sun light can also be focused on a point.