Light and Sound Wave Simulation



Light and Sound Wave Simulation

CLASS COPY! PLEASE DO NOT WRITE ON THIS PAPER!

Phet: We are going to look at some Light and Sound wave simulations today.

-First log on to your computer and go to the SHMS website. Under the student links go to Phet. Or type in the following URL:

-Next in the search box type “Wave Interference”.

-Under Simulations, click on “Wave Interference”. When it comes up click on “Run Now”

Directions: On a piece of paper, write your name, date, and period. Title the paper Light and Sound. Record your answers to the questions below on your paper.

A. Water Wave Simulator

Make sure you are on the top tab that says water. Label this section of your paper WATER WAVES. Answer the following questions on your piece of paper.

1. You will change the frequency and amplitude sliders. You will also use the Rotate View slider to change from top view to side view. Copy the chart onto your paper. Move the sliders to match the titles in each of the four boxes. Under each box you will write a description and draw pictures of what you see.

|Frequency Low |Frequency High |Frequency Low |Frequency High |

|Amplitude Low |Amplitude Low |Amplitude High |Amplitude High |

|Description: |Description: |Description: |Description: |

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|Top View Picture: |Top View Picture: |Top View Picture: |Top View Picture: |

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|Side View Picture: |Side View Picture: |Side View Picture: |Side View Picture: |

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2. Put the view to top view. Now click on the box Show graph and move the frequency and amplitude

sliders to the center position. Draw the graph and label the crest, trough, and wavelength.

3. How does the graph change when you leave the amplitude bar in the center and increase the frequency?

How does the graph change when you leave the frequency bar in the center and increase the amplitude?

4. Add a one slit barrier. Move the barrier to the middle of the pool. Set the amplitude to 50% and the

frequency to 75%. Watch what happens. Choose the width of the opening for the barrier. Describe what

happens and draw a picture.

5. Make sure you are on top view. Add a second drip. What happens when the faucets are close together?

What happens when the faucets are far apart?

B. Sound Wave Simulator

Now click on the top tab that says sound. Label this section of your paper SOUND WAVES. Answer the following questions on your piece of paper.

1. Draw what you see. Label where you think the compressions are and where the refractions are. (Compressions are where matter is pushed together and refractions are where matter is stretched out.)

2. You will change the frequency and amplitude sliders. You will also change from “Grayscale” to “Particles”. Copy the chart onto your paper. Move the sliders to match the titles in each of the four boxes. Under each box you will draw pictures of what you see for the Grayscale and for the Particles.

|Frequency Low |Frequency High |Frequency Low |Frequency High |

|Amplitude Low |Amplitude Low |Amplitude High |Amplitude High |

|Grayscale Picture: |Grayscale Picture: |Grayscale Picture: |Grayscale Picture: |

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|Particle Picture: |Particle Picture: |Particle Picture: |Particle Picture: |

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3. Go back to grayscale view. Put the sliders for frequency and amplitude in the middle. Add a barrier.

Draw or describe what happened to the wave with the barrier.

4. Keep the sliders for frequency and amplitude in the middle. Remove the barrier and add a second speaker.

Draw or describe what happened to the wave.

In classroom we will use the sound on the simulation. Today you will NOT listen to the sound on your computer. Today you will make predictions about the sound.

5. How do you think the sound will change when you increase the frequency?

6. How do you think the sound will change when you increase the amplitude?

7. What do you think you will hear if all the particles are still? Why do you think this?

C. Light Wave Simulator

Now click the top tab that says light. Label this section of your paper LIGHT WAVES. Answer the following questions on your piece of paper.

1. Click on “show graph”. Leave the amplitude in the middle. Copy the chart onto your paper. Complete the chart by moving the wavelength to the colors in the chart. Pause the graph on each color. Make sure the wavelengths have reached the end of the graph before you pause it. Count and draw the number of wavelengths that are shown in the graph.

|Red |Yellow |Purple |

|Number of Wavelengths: |Number of Wavelengths: |Number of Wavelengths: |

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|Picture of Graph: |Picture of Graph: |Picture of Graph: |

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2. What happens to the wavelength and frequency as you change the color? (Remember that frequency is

how many waves pass a certain point in a certain amount of time.)

3. Add a barrier. Move the barrier back and forth. What happens as the opening gets closer and farther

from the source? Does changing the color affect this?

4. Add a detector and still have one barrier. Set the slit width at 1050 and the barrier location at 2590. Use

the target on the detector to compare the amplitudes on each side of the barrier. Draw what the amplitude

looks like in front of the barrier and what the amplitude looks like behind the barrier.

5. Why do you think the barrier changed the amplitude?

D. Conclusions

Label this section of your paper CONCLUSION. Use the information you learned from the simulations to answer the questions on your piece of paper.

1. In the simulations you added barriers. Some examples of barriers in real life for light can be lenses,

mirrors, or a clear liquid. How do you think looking at light through some of these barriers changes the way

we see?

2. In the simulations you added barriers. A barrier in real life for sound is a wall. How do you think hearing

sound through a wall changes what you hear?

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