6  6.3.2                            What are the laws of reflection?We all know what we see when we look in a mirror – but...
6  6.3.2                            What are the laws of reflection?3 You are going to do an experiment, using the equipme...
6  6.3.2                            What are the laws of reflection?  you looked at your reflection in water with ripples ...
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  1. 1. 6 6.3.2 What are the laws of reflection?We all know what we see when we look in a mirror – but why do we seeourselves, and why is the mirror image so clear?Equipment • plain mirror • mirror holder • light source that gives a single • A3 plain paper ray • angle measurer (protractor) • rulerSafety• Handle mirrors with care – if you break one you could cut yourself on the broken pieces.• Light sources can become hot enough to burn skin.Obtaining evidence1 Look at the image of a candle in a mirror. If you look at the tiles on the floor, you can see that the candle appears to be the same distance behind the mirror as it is in front. mirror2 Now look at the diagram that represents the situation as seen from above. You will notice that light rays and angles have been given names. mirror reflected angle of light ray reflection normal angle of incidence position of candle image of candle incident light rayGo Science! 2© Pearson Education Limited 2008 1 of 3This worksheet may have been altered from the original.
  2. 2. 6 6.3.2 What are the laws of reflection?3 You are going to do an experiment, using the equipment listed above, to confirm or contradict the statement that ‘the angle of reflection is equal to the angle of incidence’.4 Use the angles shown in the diagram below for incident light. 80° 70° 60° incident light rays 50° 40° 30° 20° 10° normal mirror5 Draw a results table to record you measurements in. This will need to record the incident angle and the reflected angle6 Draw the normal, the position of the mirror and the incident angles accurately on a piece of paper. This should look very similar to the diagram above. Put the mirror along the mirror line on the paper and shine a light ray along one of the incident lines you have drawn. Draw the path of the reflected ray on the paper. Repeat this for all of the incident angles.7 Now remove the mirror and measure the angle of each reflected ray and record the results in your results table. Notice that the angles are measured between the normal and the light ray.Presenting the results1 Plot a graph of your results and add a straight line of best fit.Considering the evidence1 Using your results, write a simple statement describing the link between the angle of reflection and the angle of incidence.Evaluating2 How accurately do you think you measured the angles is? Give an answer in numbers, for example plus or minus 5°.Extension3 A flat mirror gives an accurate reflection of your face. Describe what would happen to your reflection if the mirror was not flat, for example ifGo Science! 2© Pearson Education Limited 2008 2 of 3This worksheet may have been altered from the original.
  3. 3. 6 6.3.2 What are the laws of reflection? you looked at your reflection in water with ripples on it. You might like to use sketches to help you.4 Hold this piece of paper facing you. Notice the letter F (letter 1) below is the right way up and the right way round. Now turn the paper over so that the top edge of the paper is still at the top. Notice the reversed F (letter 2), seen through the paper from the other side, now looks the right way round. Turn the paper back towards you again. Now turn the paper round so that the top of the paper is at the bottom. Now notice the letter F (letter 3) that looks the right way round. Explain why the different reversed versions of the F look right in the mirror depending on what you did to the paper. 1 2 3Go Science! 2© Pearson Education Limited 2008 3 of 3This worksheet may have been altered from the original.

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