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# Light Lesson 3

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Light, year 8, lesson 3, science

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### Light Lesson 3

1. 1. Light – lesson 3 <ul><li>Target </li></ul><ul><li>To know the effect of refraction of light and be able to explain why it happens </li></ul>
2. 2. Describe what you see when this pencil is placed in the water.
3. 3. Experiment <ul><li>Follow these instructions and look at refraction of light using the ray boxes </li></ul><ul><li>PUT THE GLASS BLOCK ON PAPER – MARK ITS POSTION WITH PENCIL </li></ul><ul><li>MARK THE RAY OF LIGHT AS IT GOES INTO AND OUT OF THE BLOCK </li></ul><ul><li>JOIN UP THE POINTS TO SHOW THE PATH OF THE RAY THROUGH THE BLOCK </li></ul>
4. 4. Experiment 1 1) Ray gets refracted 3) Ray still gets refracted but not deflected 2) Ray still gets refracted
5. 5. Experiment 2 <ul><li>Now draw the diagrams shown in your book </li></ul>Rays of light going in a glass block
6. 6. Explaining refraction <ul><li>Imagine a car driving from the road into a muddy field. </li></ul><ul><li>In the muddy field it slows down as there is more friction. </li></ul><ul><li>If it enters the field at an angle of incidence of other than 0  then the front tyres hit the mud at different times. </li></ul><ul><li>Tyre one hits the mud first and will move more slowly than tyre two.This causes the car to turn towards the normal. </li></ul><ul><li>When the car leaves the mud for the road, tyre one hits the road before tyre two and this causes the car to turn away from the normal. </li></ul>Tyre 1 Tyre2 Mud Road
7. 7. Refraction Refraction is when waves ____ __ or slow down due to travelling in a different _________. A medium is something that light waves will travel through. When a ruler is placed in water it looks like this: In this case the light rays are slowed down by the water and are _____, causing the ruler to look odd. The two mediums in this example are ______ and _______. Words – speed up, water, air, bent, medium