Refraction and reflection

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worksheet you will learn why it is that light seems to bend. ... reflection total internal reflection. To do. You will need a 20 cent coin, a glass and some water in  ...
Behaviour and Properties of Light

REFRACTION AND REFLECTION

6.1

In this worksheet you will learn about how light can ‘bend’.

In earlier years you probably learnt that light travels in straight lines. In this worksheet you will learn why it is that light seems to bend. You may have noticed when you look into a swimming pool that the legs of the people in the pool seem to be shorter than they really are. This is because light does a strange thing as it passes from one substance to another. As light passes from one substance into another it changes speed.

special words refraction reflection total internal reflection

Light travels faster in air than in glass and water. This makes light bend as it goes through these substances. This bending is called refraction.

To do You will need a 20 cent coin, a glass and some water in another glass. 1 Place the 20 cent coin in the bottom of the glass. 2 Sit so that you can see the glass and the coin from the side. Do not look down on the coin from above. 3 Slowly pour the water into the glass that has the coin in it. Stop when there is about 5 cm of water in the glass. 4 What did you notice? Write your observations in your workbook. 5 Tip out the water and try this trick again. 6 Did the same thing happen? 7 Try it one more time. 8 Write down what happened each time in your workbook. 9 Why was it a good idea to do the coin trick more than once? 10 Look at the information on this page and try to explain what you saw. 11 Try this at home and explain to your family what was happening.

© Reed International Books Australia Pty Ltd

Heinemann Achieve Science Two

Behaviour and Properties of Light

6.1

To do You can do this if there is a fish tank with water in it. 1 Look at the tank from the front and then very slowly move to a corner of the tank. 2 Keep looking into the tank as you do this. 3 Very gently and slowly move your head from side to side while you are standing at the corner of the tank. 4 Do this a few times and then write down what you could see.

5 Where did the fish go?

Refraction can cause another tricky thing called total internal reflection to happen. Sometimes as light passes from one substance to another, some of the light gets refracted back into the substance. When all the light gets internally refracted it is called total internal reflection. This happens in diamonds and we see it as sparkles. It is also why when you were looking at the corner of the fish tank some of the fish seemed to disappear! What you saw was due to total internal reflection!

Diamonds sparkle because of total internal reflection ray leaving diamond

ray entering diamond

refraction

total internal reflection

refraction

total internal reflection

You can see from this worksheet the tricks that light can play on our eyes! Heinemann Achieve Science Two

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