Name: Group members: Procedure 1: Wave propagation 1.) Consider a disturbance in still water. Perhaps a rock dropping in a lake or a faucet with a constant drip into a full sink. How does that disturbance affect the medium in both of these scenarios ? 2.) Go to the following link and verify your conclusion by selecting "Waves" under the simulation https://phet.colorado.edu/sims/html/wave-interference/latest/wave-interference_all.html. Turn the faucet on using the green button. Use the toggle button between continuous wave and pulse on the left to visualize both scenarios . Are they what you expected ? Procedure 2 : Interference 1.) Define the term "interference" in your own words: 2.) Consider two point sources of light. The waves emitte he waves emitted from these point sources oscillate in phase and have the same wavelength/frequency. Directly in between these two sources we would see: constructive interference or destructive interference (circle one). Why? 3.) Select the interference simulation at the bottom of the screen. Switch to the point sources of light (looks like a laser. Not the faucet or speaker.) Turn both light sources on and press play. What do you observe at the center between the point sources? 4.) Using the default frequency (refresh if you've changed it), set the separation of the point sources to 1800 nm. With the light sources on, you should notice what appears to be some lines that stem out from the center point between the point sources. These lines are blurry and appear to be a dark green. If you have trouble identifying the lines , ask yo What do these lines represent? How many of these lines reach the right edge of the simulation window? Procedure 3 : Slits 1.) After a plane-wave reaches a thin slit, how does the wave begin to propagate? 2.) Using your knowledge of single-slit diffraction, what is the formula for the full-width of the central maximum for single-slit diffraction? What do all the variables represent? 3.) Select the "Slits" simulation tab at the bottom. Switch over to a light source on the right. Turn the light source on so that the wave begins to propagate through one slit. Now select the screen and intensity checkboxes. These will show the diffraction pattern on a screen at the right of the simulation window. From your formula if you increase the slit width, what will happen to the width of the central maximum? Verify this with the simulation by comparing a slit-width of 500nm with 1000nm. 4.) Keeping the slit-width at 1000 nm, if you bring the slit all the way to the right of the page what happens to the width of the central maximum? Explain this using your formula.Procedure 3: Slits 1.) After a plane-wave reaches a thin slit, how does the wave begin to propagate? 2.) Using your knowledge of single-slit diffraction, what is the formula for the full-width of the central maximum for single-slit diffraction? What do all the variables represent? 3.) Select the "Slits" simulation tab at the bottom. Switch over to a light source on the right. Turn the light source on so that the wave begins to propagate through one slit. Now select the screen and intensity checkboxes. These will show the diffraction pattern on a screen at the right of the simulation window. From your formula if you increase the slit width, what will happen to the width of the central maximum? Verify this with the simulation by comparing a slit-width of 500nm with 1000nm. .) Keeping the slit-width at 1000 nm, if you bring the slit all the way to the right of the page what happens to the width of the central maximum? Explain this using your formula. 5.) Using your knowledge of double-slit diffraction, what is the formula for the position of the bright fringes on the screen? What do all the variables represent? 6.) If you increase the slit separation what will happen to the positions? Verify this by refreshing the d selecting slits. Then select two-slits from the drop down on the right and check the creen and intensity boxes . 7.) If you increase the wavelength what will happen to the positions of the bright fringes? Verify this by comparing the frequencies of red and blue light. Keep in mind that red light has a larger wavelength than blue light . Procedure 4: Circular apertures 1.) What is the formula for the full width of the central maximum for diffraction from a circular aperture? What do all of the variables mean? 2.) You have an adjustable circular apen le circular aperture (an iris) on an optics table with a collimated beam illuminating it. If you decrease the radius of the opening, what will happen to the diffraction pattern on the screen behind the aperture? 3.) Verify your answer to the last question by using the diffraction tab at the bottom of the screen and adjusting the diameter. 4.) Play around with the other variables and have fun with the simulation. There are others as well t.colorado.edu. They are pretty neat. When you're done, be free :)