Plane Mirrors Lab
Purpose (record in your lab book, under the title): To diagram the law of reflection using lasers and protractors
How can we diagram the law of reflection?
You will need: laser, wooden box with mirror on it, protractor, graph paper
Procedure:
Analysis:
Conclusion:
Write a paragraph conclusion pertaining to this lab. What did you think of it? How could it be improved? Were there any errors? How did you prove or refute the law of reflection?
How can we diagram the law of reflection?
You will need: laser, wooden box with mirror on it, protractor, graph paper
Procedure:
- Using a pencil, draw a straight line on your graph paper. Label it “mirror”.
- Mark a central point on the line where the graph paper’s grid intersects your line, and label it “reflection point”.
- Using your pen and protractor, draw the normal line. The normal should be perpendicular to the “mirror” line at the reflection point. Label the normal line “normal”.
- Using the protractor and pencil, draw an incoming angle into your “reflection point”. You may choose an angle between 20 and 50 degrees from the normal. Label this new line “incident ray”.
- Using the protractor, measure the angle between the “incident ray” and the “normal”. Write the angle measurement on your graph paper.
- What do you think will happen when the laser’s incident ray strikes the mirror? Draw a dotted line to represent your “hypothesis ray”.
- Place the flat mirror so the back of the mirror is on the “mirror” line. On the graph paper, carefully trace a pencil line along the front side of the mirror. This line marks the edge of the glass surface.
- Turn the laser pointer on. Never look directly at the laser beam or allow it to shine in someone's eyes. Use the binder clip to maintain the laser pointer in the ON position. If you need help seeing the laser beam, ask your teacher for assistance. Make sure that the laser beam follows the “incident” line, and clearly shows a reflected beam on the other side of the normal line.
- Mark the reflected laser ray in several places (at least 3) along the laser’s reflected beam. Do not disturb the laser pointer’s position. Turn the laser pointer off when you are done.
- Using your protractor, line up the reflected ray’s marks, and draw a straight line that intersects the “mirror” line. Measure the angle between the reflected ray and the normal.
- Sketch the diagram on the graph paper into your lab book, complete with normal line, incident ray, hypothesis ray, and reflected ray, and measured angles.
Analysis:
- Did the law of reflection work with the glass mirror? Explain. (Cite your angle with the normal from your incident ray and your reflected ray.)
- Based on your data, where do you think the actual reflection point lies on the “mirror” line?
- What do you think happened to the incident laser beam inside the glass mirror based on your observation data?
- How does the law of reflection allow you to see around a corner?
Conclusion:
Write a paragraph conclusion pertaining to this lab. What did you think of it? How could it be improved? Were there any errors? How did you prove or refute the law of reflection?