Lab 15: What is the relationship between the angle of incidence and the angle of reflection?
If time allows: What are the characteristics of images formed in a plane mirror? How is a virtual image formed? What is the field of vision for a given location in front of a plane mirror?
Available Materials: Pins, corkboard, mirror, protractor, straight edge, compass, pencil, white paper.
Instructions:
1. Label a sketch of the mirror, labeling all features that you possibly can.
2. How will you measure the angles of reflection and incidence? Which should be your independent variable? Design a procedure, noting down the steps in order, leaving some space for corrections. Also note any assumptions that you must make. After these instructions, there are some suggestions for how to use the equipment to its best advantage.
3. Record all measurements, using a data table. If you are not sure about the design of your data table, you can organize your information later. Just be sure to label everything clearly.
4. Show all calculations clearly.
5. How will you measure the characteristics of the images? What variables affect these characteristics? Design a procedure, noting down the steps in order, leaving some space for corrections. Also note any assumptions that you must make.
6. Is a graph appropriate in this lab? What graphs should you make to represent the relationship or to check your results? If you think it necessary, create these and explain their meaning.
7. Is there a way to compare the results with a “correct” answer? Find percent error or percent difference whenever it is appropriate. Show your work.
SOME OTHER INFORMATION:
· You will be judged on your experimental design, on the quality of your data, and the accuracy/precision of your results.
· Record everything you do, think, and measure in your lab journals. You never know what you will need during the analysis.
· Work with your group, thinking out loud, and help each other to understand what you need to do to accomplish this.
Suggestions for using the materials and equipment:
1. Place a sheet of paper on the corkboard. Place the mirror on top of the paper as in the picture to the right. Look at one side of the mirror and locate the position where the black support meets the mirror. Place a small dot on the paper to mark this position. Repeat this step for the other side of the mirror.
2. Remove the mirror from the paper and use a ruler to connect the two dots. This line represents the position of the mirror, since this is a rear surface mirror. Replace the mirror on this line, such that the mirrored surface lies along it.
3. Place a pin approximately 12 cm in front of the mirror and approximately 7 cm to the right of center. Label this position "A." Choose a point on the left side of the mirror and label it "B." Draw an eye at this position. Position your eye behind the eye at position "B" such that the image from pin "A" is in line with the eye at position "B." In order to see the image of pin "A," a light ray has to leave pin "A" and reach your eye at position "B." Use a straight edge or ruler to draw the path of the light ray as it leaves pin "A," reflects off the mirror, and reaches your eye at position "B." Draw a dashed line perpendicular to the mirror where the ray reflects from the mirror. This is called a normal line. Using a protractor, measure the angle of incidence and the angle of reflection.
4. Repeat these steps as many times as you deem necessary at various positions.
5. Remove the mirror from the paper and use a straight edge to extend each of the reflected light rays behind the mirror. Use dotted lines to illustrate that the light rays from pin "A" don't actually go through the mirror.
1115 Lab 15 Reflection of Light in a plane mirror 2006 DE