Llaves

Waves: Reflection and Interference
Course: 1st Semester Algebra/Trig Course

Learning Goals
1. Differentiate between the reflection of a 1-D transverse wave at fixed and at open boundaries
2.Describe interference of single pulse overlapping
3. Identify where peaks and valleys occur in interference patterns

Simulations Used
Waves on a String
Sound

Environment:
Group Activityduring lab period

Activity
I. Observe Reflection of Pulses at Different Boundary conditions
1. Open Waves on a string.
2. Launch single transverse pulse (damping = 0 , tension = max BC =fixed)
Observe phase of reflected pulse.
3. Make prediction if pulse is launched in opposite direction. What will the reflected pulse look like?
4. Test prediction with simulation
5. Change BC toopen and have students predict orientation of reflected pulse
6. Have students test prediction for pulses launched in both directions.
7. Have students summarize behavior of pulses reflected atdifferent types of boundaries
8. Explore effect of varying pulse duration, amplitude and so on

II. Observe Interference of two pulses
1. Open Sound Simulation
2. Choose interference byreflection tab
3. Set wall to vertical and choose single pulses
4. Launch two single pulses and pause them just before the reflected first pulse overlaps the incoming second
5. Use the step button toadvance the pulses and describe the appearance as the different parts overlaps
6. Identify when the overlap is maximum and minimum
7. Explore effects of varying amplitude and frequency

III.Observe two source interference pattern
1. Click on two source tab
2. Run it and run with it

Connections
1. Where have students seen interference patterns before?
2. Where have students seenreflected waves before?

Extension
1. Have students predict the behavior of a pulse on a slinky launched at fixed and free BC’s
2. Students test predictions
3. Have students predict behavior of...