Wave Lab

Waves: in atoms, in water, in your hands Mr. Bartelt’s chemistry class Introduction: Wave behavior has boggled the minds of many scientists for centuries. In this lab activity you will create a series of waves with a rope. Based on the rate at which you rotate your rope you will be able to control the frequency and the wavelength of that wave. From this you will gain an understanding of the relationship between energy, frequency and wavelength, and wave motion. Purpose: This experiment aims to determine the relationship between energy, frequency, and wavelength of a wave. This is accomplished by replicating electron wave motion with a length of rope. Equipment/Materials: > Pen > Lab sheet > Rope > Meter stick Safety: Close-toed shoes must be worn at all times. Procedure: 1. Obtain a length of rope from your instructor 2. Using a meter stick, measure out two meters of rope 3. Have one member of the lab group hold the end of the rope steady where you measured. 4. Have another member of the group swing the rope so that it forms one sweeping arch (like a jump rope). Stand so that the rope hangs with a reasonable amount of slack (the rope should hang at about a 30 degree angle from the horizontal). Do not use your whole arm to cause the rope to swing. Try to only move your wrist and elbow. 5. Try to rotate the rope as slowly as possible without allowing the rope to collapse. 6. Once you are confident in the shape of your wave ask your instructor for permission to begin recording you data. Only after you receive approval begin recording your data. 7. Have one group member keep track of the time and the rest of the group members count the number of rotations that elapse over the course of a minute (you need to be exact). 8. Record the average of all observers. 9. With your instructors assistance rotate the rope in such a way that two waves are formed instead of just one. 10. Repeat steps 5-8 11. Rotate the rope in such a way that 3 waves form. Repeat steps 5-8 12. Measure out the rope to 2.5 meters. Repeat steps 3-11. 13. Measure out 3 meters of rope. Repeat steps 3-11. 14. When you’ve finished compare results with the rest of the class. Your data should be recorded on the left hand side of each box. Class averages are to be recorded at right. Class averages will be determined in class. Wave lab Revised on 10/14/08 (Mr. Bartelt)

Waves Data Table Data Table:

Complete this table using the information provided in the procedure and introduction to the lab. 2 meters

2.5 meters

3 meters

Yes or no

Yes or no

Yes or no

1 sweeping wave 2 waves 3 waves Are 4 waves even possible? Average for 1 wave Average for 2 waves Average for 3 waves Questions (to be addressed in conclusion):

1) How far was your data from the class average? 2) Did most of the class have similar answers? 3) What does this suggest about the nature of waves? 4) If the number of rotations per minute is analogous to the amount of energy in a wave, then which set of waves (that you created in this experiment) required greatest amount of energy to create? Which required the least to create? hc 5) Does this support the formulas c = λv , E = hv , and E = ? λ Wave lab Revised on 10/14/08 (Mr. Bartelt)