# Right Angle Mirror

 Materials: Computer and School Network; Protractor and Ruler Time Allotment: 3 Class Days

### Purpose:

The purpose of this lab is to use the law of reflection and ray diagrams to investigate how images are formed by right angle mirrors and to compare the features of the various images.

1. Log on to the server in the usual manner.
2. Open the HyperCard application found in the Multimedia folder.
3. From the File menu, choose Open... . A directory dialogue box will open. Navigate to the Physics Stacks and open the file titled Right Angle Mirrors.

Click anywhere on the title card of the stack. By so doing, you will navigate to the main card. A miniature snapshot of the appropriate card is shown below. Directions are included in the text field on the left side of the card.

### Part 1: Image Formation by Right Angle Mirrors

1. Upon reading the on-screen directions, click on three spots between the right angle mirrors. After each click, three lines of sight will be drawn. Each line of sight corresponds to the direction in which an eye must look to view each image.
2. Once three eye locations have been chosen and three lines of sight corresponding to each of the three eye locations have been drawn, print the diagram. This diagram will subsequently be used for the completion of the lab.
3. Using dashed lines, extend each of the lines of sight backwards beyond the mirror. You should notice something distinct about these extensions lines. This will help you later on the post-lab questions and the conclusion.
4. For each line of sight (representing a light ray reflected from the mirror to a given eye location), draw the corresponding incident rays. Use a protractor and be as accurate as possible. Some of the light rays actually undergo a double reflection on the way from the object to the eye. Show this by completing the ray tracing for all light rays which begin at the object, travel to the mirror and reflect to the eye. Place arrows upon all light rays to indicate their direction of travel.
5. You have completed your diagram for Part 1. Submit the completed diagram with this lab sheet. Use the diagram to answer the post-lab questions.

### Part 2: Comparison of Images Formed by Right Angle Mirrors

1. Click on the button titled "To Part 2." A new card will appear which looks as follows.

2. This card allows you to view the appearance of various images as viewed in a right angle mirror. The front view of what you would see in the various faces of the mirror is shown at the left and a top view of the situation is shown at the right. Buttons can be used to change the face of the mirror and to raise the left or the right hand. Click on the various buttons and make observations, comparing how the middle images differ from those seen in the side faces of a right angle mirror.

Record some observations below. Use your observations to assist with the post-lab questions below.

### Post-Lab Questions:

1. Describe what you observe about the extensions of all lines of sight.

2. If all students in a classroom look at the left image of a candle in a right angle mirror, will they all look in the same direction? ________ Justify your answer.

3. Describe the location of the three images formed by a right angle mirror by comparing the distance from the object to the mirror to the distance from the image to the mirror.

4. Draw a line is from the object through the crease of the mirror. Describe what you notice.

5. Draw a generalization about what each light ray which undergoes a double reflection have in common.

6. Explain how the middle image in a right angle mirror differs from the side images.

7. If you were to look at the three images of your NIKE shirt in a right angle mirror, what would you observe? Explain fully.

8. For the following set of mirrors, locate all images. Show all ray constructions clearly.

9. On the following diagram, locate the three images of the object and show how light travels from the object to the eye in order of the eye to view the middle image of the given object.

### Conclusion:

Describe in detail how light rays from an object can produce three images for right angle mirrors. Be extensive and use the language of physics. Then compare the features of the various images in a right angle mirror and provide an explanation of why the middle image differs from the other two. Do a bang-up job!