Exploring-Light-as-a-wave-20210126

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Physics Experiment: Light as a Wave
Name:								Date:				
Part 1: Diffraction
1) Go to: phet.colorado.edu
2) Roll over “SIMULATIONS and click on “Physics”
3) Scroll down to “Waves Interference” and click on it. 
4) Click on: 
5) Click on: 
6) Get familiar with all the controls, make changes, interact with the simulation.
7) Now that you are familiar with the simulation, select the box ; adjust the width and height so you get a tall, narrow opening 
8) Select a wavelength near one end of the color spectrum – you choose and then turn on the light 
9) Describe the diffraction pattern that appears:
10) How is the diffraction pattern oriented, relative to the opening?
11) Now make the opening short and wide.
12) Describe the diffraction pattern that appears:
13) How is the diffraction pattern oriented, relative to the opening?
14) Now max out the width and height of the opening
15) Describe the diffraction pattern that appears:
16) How is the diffraction pattern oriented, relative to the opening?
17) Now minimize the width and height of the opening.
18) Describe the diffraction pattern that appears:
19) How is the diffraction pattern oriented, relative to the opening?
20) Now, change the wavelength to the other side of the spectrum. For example, if you chose the red end of the spectrum for the previous steps, move the wavelength slider to the blue end of the spectrum.
21) Describe the diffraction pattern that appears:
22) How is the diffraction pattern oriented, relative to the opening?
23) How does this diffraction pattern compare to the diffraction pattern of the previous color?
24) Now max out the width and height of the opening
25) Describe the diffraction pattern that appears:
26) How is the diffraction pattern oriented, relative to the opening?
27) How does this diffraction pattern compare to the diffraction pattern of the previous color?
28) Now make the opening short and wide.
29) Describe the diffraction pattern that appears:
30) How is the diffraction pattern oriented, relative to the opening?
31) How does this diffraction pattern compare to the diffraction pattern of the previous color?
32) Now make the opening tall and narrow.
33) Describe the diffraction pattern that appears:
34) How is the diffraction pattern oriented, relative to the opening?
35) How does this diffraction pattern compare to the diffraction pattern of the previous color?
36) Explain how this shows light behaves like a wave.
37) Get a screen shot or picture of your setup
Part 2: Interference
1) Down at the bottom, select 
2) Select light 
3) Set Amplitude in the middle
4) Turn on:
a. Screen
b. Intensity 
5) Pick a color with the frequency slider and write the color you chose.
6) Turn on only one of the lights .
7) Describe how you can determine the wavelength of the color of light you chose using any or all of the tools and controls in the simulation.
8) Now go figure out the wavelength of the light you chose and write it here________. Be sure and put correct units on it!
9) Calculate the frequency of the color of light you chose (you may need to check your notes or the textbook to find an equation to use). Write the frequency of the color you chose, here here________. Be sure and put correct units on it! 
10) If you changed the Amplitude, set it back to the middle and describe the intensity chart.
11) Now, max out the Amplitude. How did the intensity chart change?
12) Pick a new color with the Frequency slider. After letting the waves propagate across, describe how the intensity chart compares to the previous color.
13) Turn on the other light and let the waves propagate across. Describe the intensity chart; how many “bumps” appear and how tall are they compared to the previous intensity chart?
14) Change the Amplitude back to the middle. Describe the intensity chart; how many “bumps” appear and how tall are they compared to the previous intensity chart?
15) Now, max out the separation (4000 nm) and let the waves propagate across. Describe the screen at the right side of the simulation (next to the intensity chart) and the intensity chart.
16) Vary the Amplitude; describe what affect it has on the screen and the intensity chart.
17) Vary Frequency; describe what affect it has on the screen and the intensity chart.
18) What settings can you change in the simulation to change the number of colored lines on the screen?
19) Adjust the settings on the simulation to get the brightest and most lines on the screen. List your settings, here:
20) What causes the alternating dark and colored areas on the screen at the right side of the simulation (next to the intensity chart)?
21) Explain how this demonstrates light behaves like a wave.
22) Get a screen shot or picture of your setup
Part 3: Slits
1) Down at the bottom, select 
2) Select light 
3) Turn on:
a. Screen
b. Intensity 
4) Based on your experience in parts one and two of this lab, describe what you expect to happen to the light pattern as you vary the number of slits, the width of the slits, and the separation between the slits.
5) Pick a color to use. What color did you choose?
6) Set Amplitude to maximum.
7) Turn on the light generator.
8) Determine the wavelength and frequency of the color you chose.
 = _____________ (don’t forget to put correct units on your answer)
f = _____________ (don’t forget to put correct units on your answer)
9) Set the simulation for 1 slit with a width of 200 nm. Describe what appears on the screen and the intensity chart.
10) What do you expect to happen if you lower the Amplitude?
11) Set Amplitude in the middle. Did it do what you expected it to?
12) DON’T MOVE ANYTHING YET! Notice near the bottom of the simulation the double green arrows. DON’T MOVE ANYTHING YET! Those will move the position of the slit to the left or right. BEFORE MOVING THE SLIT, what do you think will happen to the screen and intensity chart if you move the slit to the left (closer to the light source)? What do you think will happen to the screen and intensity chart if you move the slit to the right (farther from the light source)?
13) Move the slit closer to the light source and describe what you see on the screen and intensity chart.
14) Move the slit farther from the light source and describe what you see on the screen and intensity chart.
15) What changed on the screen and intensity chart when you moved the position of the slit?
16) Put the slit back half-way between the light and the screen.
17) Set the simulation for 2 slits, 200 nm slit width, and slit separation of 1600 nm.
18) Describe what you see on screen and intensity chart.
19) Change the slit width to 400 nm. Describe what you see on screen and intensity chart.
20) Change the slit width to 800 nm. Describe what you see on screen and intensity chart.
21) What changed on the screen and intensity chart as you increased the slit width?
22) Change the slit separation to 2400 nm. Describe what you see on screen and intensity chart.
23) Change the slit separation to 3200 nm. Describe what you see on screen and intensity chart.
24) Using the double green arrows, ,move the slit closer to the light source and describe what you see on the screen and intensity chart.
25) Now, move the slit farther from the light source and describe what you see on the screen and intensity chart.
26) What changed on the screen and intensity chart when you moved the position of the slit?
27) Adjust the settings on the simulation to get the brightest and most lines on the screen. List your settings, here:
28) Get a screen shot or picture of your setup
Part 4: Summary
Explain, in complete sentences, how Young’s Double Slit experiment (diffraction, wave interference, etc.) demonstrates light behaves as a wave.
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