PHYS 112 Lab: Wave Interference
PhET simulation – Wave Interference
https://phet.colorado.edu/en/simulation/wave-interference
Part A: Open the “Wave Interference” simulator. Click on the option, “Waves.” (We will try “Interference” and
“Slits” later in the lab.) Your dashboard should now match the settings below:
1) Experiment with the settings and choose the view that you prefer (“Top View” or “Side View”.) Try
checking the “Graph” box and watch how the plot is related to the amplitude of the wave.
2) Set the frequency to the minimum. Use the timer to measure how long it takes for the wave to travel
the length of the box, and record it here (don’t forget your units!): 8 seconds
3) Set the frequency to the maximum. Use the timer to measure how long it takes for the wave to travel
the length of the box, and record it here (don’t forget your units!): 6 seconds
4) Now switch to observing sound waves (press the speaker icon). Experiment with viewing the wave
propagation as Waves, Particles, and Both. Your screen may look something like this:
1● Observe the motion of an individual particle (choose a random red dot). What can you say
about its motion as the waves pass by?
As the wave passes by the red dot is pushed away then pulled back in.
● What are the particles doing when no sound pulse is traveling through? What makes it realistic?
The particles have no waves coming through to move them. This makes sense because there is no
sound to be moving significantly.
5) Set the frequency to the minimum. Do your best to estimate the wavelength using the
measurements on the measuring tape widget and record it here (don’t forget your units!):
_52 cm_
(Measuring tape widget)
6) Set the frequency to the maximum. Measure the wavelength and record it here (don’t forget your
units!): 34 cm
7) Now switch back and forth between Top View and Side View. What do you observe, and why do you
think it appears this way?
There is no difference because sound travels parallel to direction.
8) Next, experiment with the laser. What happens to the color when you change the frequency?
When you change frequency, color changes.
9) Use the measuring tape widget to estimate the wavelength of the light waves produced using the
following frequency settings (don’t forget your units!):