Reflection, Refraction, and Diffraction Lab
The purpose of this lab is to investigate wave interactions. Below are various procedures that you will conduct for this lab. In addition to carrying out the procedures, you need to write a formal lab report. Use the information below to help guide you through writing your lab report.
1. Write an introduction paragraph related to wave interactions. Include information about the different ways that waves can interact and why they interact. You can also include any experiences you have had with wave interactions such as echoes.
Introduction Paragraph:
2. Procedures. Procedure 1: Tennis Ball Angles Materials Needed: tennis ball, wall, masking tape, meter stick or protractor.
1. Sit on the floor and roll a tennis ball toward a wall directly in front of you. Mark this line as the normal line as this will serve as your reference. (Note: it should be perpendicular to the wall.) 2. Roll the ball at increasing angles to the normal line. Measure the angle you will release the ball from the normal line (Angle of Incidence) and measure the angle the ball bounces off the wall (Angle of Reflection). The best way to measure is to use a protractor so you can measure the angle. However, if you do not have a protractor then use a meter stick or ruler to measure the distance from where you released the ball to the normal line and then from the normal line to where the ball reflected. It is important that you measure at the same spot so that your measurement will be an accurate representation of the angle. Look at the picture below for a visual explanation.
3. Record measurements in the data table below. Repeat procedure more times from various angles.
Bounce Number Angle of Incidence Angle of Reflection 4. Answer the following Analysis Questions: What do you notice about the angle of incidence and the angle of reflection? What can you conclude about the reflection of light based on this demonstration? How would the information you learned from this lab improve a person’s pool game? Provide an explanation on how other waves show reflective behavior (such as sound waves and ocean waves).
Procedure 2: Pencil in a Glass Materials Needed: pencil or straw, clear glass, water. 1. Place a pencil (or straw) in a clear glass of water. 2. Observe the pencil from the front of the glass. (Bend down so the glass is at eye level). 3. Rotate the glass and make observations. 4. What do you notice about the pencil? ______5. Draw a picture of the pencil and the glass. Draw the normal line and label the angle of refraction.
6. Answer the following Analysis Questions: What is happening to light waves to cause what you have observed? Which type of wave interaction is being demonstrated here (reflection, diffraction, refraction)?
Procedure 3: CD producing Rainbow Materials Needed: CD without any labels. 1. Use the label side of the CD and use a piece of tape to rip off the protective coating and the reflecting layer. If it does not peel off, with the help of an adult, use a sharp tool to scratch off a small portion on the edge of the CD and then peel off the rest of the layer using adhesive tape. 2. Hold up an unlabeled CD to the light until you see a rainbow. 3. Answer the following Analysis Questions: What is happening to the light waves to cause you to be able to see a rainbow? Which type of wave interaction is being demonstrated here (reflection, diffraction, refraction)?
3. Write a conclusion paragraph. In the paragraph state whether your data supports or refutes the definitions for reflection, refraction, and diffraction. Discuss any modifications you would do if you conducted the various procedures again. Discuss how accurate and precise your measurements were and if there was anything that could be done different to improve your measurements. Talk about what you have learned by conducting this experiment.
Conclusion Paragraph:
Lab adapted from http://studentorgs.vanderbilt.edu/vsvs