Light and Sound Wave Simulation
Name:______________________________________________
We are going to look at some Light and Sound wave simulations today. First log on
to your computer and type in the following website:
http://phet.colorado.edu/new/simulations/index.php?cat=Sound_and_Waves
You have to make it look exactly like above.
Next Click on the “Wave Interference” simulator and click “Run Now”
A. Water Wave Simulator
First you are going to record your observations about the water wave simulator.
1. What happens to what you see as you move the frequency and amplitude
sliders?
Frequency changes the number of
waves while amplitude changes the
amount of energy the waves have.
2. Now click Show graph and repeat. What do you notice with the graph of the
water level? (Use terms like amplitude, crest, trough, wavelength, and
frequency)
You can see the change in the number
of waves when you change the
frequency. When frequency increases,
wavelength decreases so you have
more waves. When frequency
decreases wavelength increases so you
have more waves.
When amplitude changes it affects the
distance between the crest and the
trough of the wave. More amplitude
means there is more energy.
3. Now rotate your view of the water. Record your observations.
The actual water looks just like the
graph!
4. What happens if you add a second drip? What happens if you space them
close together? Far apart?
With two drips close together, there is more
energy. With the two drips far apart, there are
areas where the waves come together and add
their energy to each other and areas where they
subtract.
5. Turn off the second drip but add a barrier. Record your observations. What
happens as you alter the width of the slit?
The water bounces (reflects!) off the
barrier and back but diffracts through the
slit. The small the slit the larger the bend
(diffraction).
B. Sound Wave Simulator
Now click on the top tab that says sound.
1. What do you see?
Compressions and rarefactions.
2. What happens when you press the particle button? What happens to the
particles as you alter the frequency and amplitude? Record your observations.
The particles show how the sound hits
the air particles and move them to
create waves. The higher the
frequency, the more energy is shown
and the more waves (shorter
wavelength). The higher the
amplitude, the more energy shown but
the amount of waves does not change.
3. Click show graph. What happens to the graph as frequency and amplitude are
The higher the frequency, the
more energy is shown and the more
waves (shorter wavelength). The
higher the amplitude, the more energy
shown but the amount of waves does
not change.
changed?
4. Click on grayscale. What happens when you rotate the view? Record your
Longitudinal waves do not look
different from any angle.
observations.
5. What happens when you turn the speaker off?
No sound, therefore no waves.
6. Turn the speaker back on after all the particles become still.
7. Turn on the sound. What happens to the sound as you vary the frequency and
amplitude?
Change the frequency and you change the
pitch (how high or how low the sound).
Change the amplitude and you change the
loudness of the sound.
8. Put the sliders for frequency and amplitude in the middle. What happens if
you add a barrier? What if you alter the barrier? What if you add two?
The sound will reflect off the barrier and echo
back.
C. Light Wave Simulator
Now click the top tab that says “light”
1. Click “show graph” and “add detector”
2. What happens when you vary the amplitude? What happens if you put the
amplitude at 0?
Amplitude determines how bright the
light is. Also no amplitude and no
frequency means no waves.
3. What happens to the wavelength and frequency as you change the color?
The frequency and wavelength change.
4. What can you say about the difference in colors? The frequency
and wavelength determine the color of the
wave.
5. Now add a slit. Move the slit back and forth. What happens as the slit gets
closer and farther from the source? Does changing the color affect this?
The amount of diffraction has to do with
where the opening is in respect to the source
and the color since color affects the
wavelength
6. Now set the slit width at 1050 and the barrier location at 2950. Use the target
on the detector to compare the amplitudes on each side of the barrier. What
happen directly behind the opening versus behind the barrier?
The area behind the opening fills first
with light then it slowly diffracts
around the edges.
7. Click “Show Screen” and “Intensity Graph.” What do you think these
represent and are showing?
Now take the information you have observed using this simulator and write your
conclusions. How do you think altering factors like wavelength and frequency affect
they way we see and hear? How does this help us understand how things like lenses
and walls can alter the way we see certain lights and hear certain sounds?