Name: Date: IST9 Per: Mr. Calder Phet Wave on a String Simulation In this simulation, you will investigate the properties of waves and how changing one characteristic of a wave affects the other characteristics. I. Pre-Lab Before you get a computer, label the following diagram based on the definitions given: Rest Position: The position of the medium when there are no waves in it. It is represented by a flat horizontal line that passes through the middle of the waves. Crest: The highest point on a wave. Trough: (say trawf ) The lowest point on a wave. Amplitude: The distance from the rest position to the crest of a wave. Wavelength: The distance from one crest to the next crest II. Starting the Simulation Sign out a computer. Phet Wave on a String 2.04 1. Use Google to search for: 2. Click on the first link
III. Exploring the Simulation 1. Explore the simulation and complete the following checklist: Wiggle the Wrench. Adjust the Damping. Set to Set to Set to Adjust Amplitude and Frequency Set to Adjust Amplitude and Pulse Width Adjust Tension 2. What happens to the wave when Damping is on a high setting? 3. Summarize one other change that occurred when you tried out different settings: 4. When a wave passes through the medium, in what direction does the wave s Energy travel? 5. When a wave passes through the medium, in what direction does a particle in the medium travel? 6. This type of wave is called a transverse wave (a word that means at a right angle to the long axis ). What is transverse about a transverse wave?
IV. Setting up the simulation for the experiments 1. You need to be on and. 2. Your screen should be set up like this: V. Measuring Amplitude, Wavelength, Wave Speed, and Frequency. 1. Press the Restart button. 2. Measuring Amplitude: Hit the Pause button and then use the Step button until the first green ball is at its highest point. Use the vertical ruler to measure the distance from the rest position to the middle of the first green ball. Record the Amplitude: 3.5 cm 3. Measuring Wavelength: With the simulation still Paused as step 2, Use the horizontal ruler to measure the distance from the middle of the first green ball (the first crest) to the next crest. Record the Wavelength: 32.5 cm 4. Measuring Wave Speed: With the simulation still Paused as steps 2 & 3, reset the timer and then press the start button on the timer. Use the Step button to advance the simulation until the timer reads 1.00 s, and measure the horizontal distance the wave has travelled in that time. Record the Wave Speed: 59 cm/s 5. Measuring Frequency: With the simulation still Paused, use the Step button until the first green ball is at its highest point. Reset the timer and then press the Start button on the timer. Use the Step button to advance the simulation until the first green ball returns to its crest position 5 times. Observe the time on the timer. Divide the number of waves that passed (5) by the amount of time on the timer to get the Frequency in waves per second. Record the Wave Frequency: 1.8 waves/s
6. Check the values you got for Amplitude, Wavelength, Wave Speed and Frequency with your teacher to be sure that you are measuring these values correctly before proceeding. VI. The effect of Amplitude on Wavelength and Wave Speed 1. Use the following Constants: Frequency = 50, Damping = 0, Tension = High. 2. Make the measurement necessary to fill in the following data table: The Effect of Amplitude on Wavelength and Wave Speed Amplitude Setting Amplitude (cm) Wavelength (cm) Wave Speed (cm/s) 20 3.5 cm 33 cm 59 cm/s 30 5.5 cm 33 cm 59 cm/s 40 7 cm 33 cm 59 cm/s 50 9 cm 33 cm 59 cm/s VII. The effect of Frequency on Wavelength and Wave Speed 1. Use the following Constants: Amplitude = 50, Damping = 0, Tension = High 2. Make the measurement necessary to fill in the following data table: The Effect of Frequency on Wavelength and Wave Speed Frequency Setting Frequency (waves/s) Wavelength (cm) Wave Speed (cm/s) 20 0.72 waves/s 82 cm 59 cm/s 30 1.08 waves/s 54 cm 59 cm/s 40 1.45 waves/s 40 cm 59 cm/s 50 1.8 waves/s 32 cm 59 cm/s
VIII. The effect of Tension on Wavelength and Wave Speed 1. Use the following Constants: Amplitude = 20, Damping = 0, Frequency = 20 2. Make the measurement necessary to fill in the following data table: The Effect of Tension on Wavelength and Wave Speed Tension Setting Frequency (waves/s) Wavelength (cm) Wave Speed (cm/s) 7 0.72 waves/s 21 cm 15 cm/s 8 0.72 waves/s 26 cm 20 cm/s 9 0.72 waves/s 39 cm 29 cm/s 10 0.72 waves/s 79 cm 57 cm/s IX. Conclusions - Answer these questions Individually. 1. What effect does wave Amplitude have on Wavelength? (Your answers should have the following format: When the Amplitude of a wave is increased, the Wavelength of the wave... ) 2. What effect does wave Amplitude have on Wave Speed? 3. What effect does wave Frequency have on Wavelength?
4. What effect does wave Frequency have on Wave Speed? 5. What effect does Tension have on Wavelength? 6. What effect does Tension have on Wave Speed? 7. For each Frequency setting in part VII above, multiply the Frequency by the Wavelength: Frequency X Wavelength = 0.72 X 82 = 59 1.08 X 54 = 59 1.45 X 40 = 59 1.8 X 32 = 59 What do you notice about the product of the Frequency of a wave and the Wavelength? The product of the Frequency and the Wavelength is constant and is equal to the Wave Speed Fill in the blank with the words that makes the equation true: Frequency X Wavelength = Wave Speed 3.5 33.0 59.5 1.8