Exercise 1.3: Ray Diagrams

Exercise 1.3: Ray Diagrams


Experiment Time - Studying Reflecting Light

In this activity you will set up an experiment to infer the 'law of reflection' from your observations. Before you begin, examine the following website.

Materials: A light box (we can make one out of a flashlight), a small mirror, a ruler,protractor, pencil and paper.

Procedure: Cut a square piece of thin cardboard. Make it larger than the end of the flashlight. Cut a narrow slit in it and then tape it over the end of the flashlight. Go to the protractor web site above and print one out if you don't have one. Then all you need to do is cut it out and use it. Read pages 194 - 199 of your textbook and complete the investigation on page 195.

1. How does the angle of incidence compare with the angle of reflection? 
2. What happens to the angle of reflection when you increase the angle of incidence?. 
3. Now that you have an idea of how light reflects, how could you use this information? Give an example of building a device that might require knowledge of the law of reflection.

So what did you discover?

The 'law of reflection' states: the angle of incidence of a ray equals the angle of reflection.