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Unformatted text preview: Interference Phenomena Prelab Figure 1: Young’s Double Slit Experiment 1 Young’s Double-Slit Experiment A beam of red light of wavelength 700 nm shines on a pair of narrow slits of sep- aration 176 μm . The light falls on a screen 0.8 m away from the slits. Sketch the resulting interference pattern (see Figure 1), and calculate the separation between bright and dark bands on the screen. You will need equation 21 in your lab manual, y m = Lmλ d Here m = 0 , ± 1 , ± 2 , ± 3 ... . This equation tells you the position y of the bright bands in the interference pattern. 1.1 Setup and Parameters The two slits are set into a screen. The distance d between the two slits is d = 176 μm Remember that one micrometer ( μm ) is 10- 6 meters . The screen with the slits in it is placed a horizontal distance L away from a second screen, L = 0 . 8 m You will view the interference pattern as a series of light and dark bands on this second screen (see Figure 1). λ is the wavelength of the red light. What is λ ? 1 Remember that one nanometer (nm) is 10- 9 meters . The integer m tells you which bright band (which maximum ) you are looking at. For ex- ample, if m = 0 then y = 0 The maximum y occurs at y = 0. This bright central maximum thus defines the origin of your y-axis. The maxima y 1 , y 2 and y 3 will be above the origin; the maxima y- 1 , y- 2 , and y- 3 will fall below the origin. 1.2 Maxima Calculate the height y 1 of the maximum m = 1. (Since you will be measuring this distance with a ruler, you should expect it to be a few millimeters or a few centimeters.) What are the heights y m of all the other bright bands in terms of y 1 and the integer m ? 1.3 Minima The dark bands will fall between the light bands. In other words, the first dark band y 1 will fall between the first two bright bands, y and y 1 . At what distance y 1 (in millimeters) will the...
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- Winter '07
- Light, Wavelength, Orders of magnitude, Thomas Young, dark bands