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**Unformatted text preview: **Assignment 10 Due: 11:59pm on Thursday, July 7, 2011 Note: To understand how points are awarded, read your instructor's Grading Policy . [Switch to Standard Assignment View ] ± Understanding Two-Source Interference Learning Goal: To understand the assumptions made by the standard two-source interference equations and to be able to use them in a standard problem. For solving two-source interference problems, there exists a standard set of equations that give the conditions for constructive and destructive interference. These equations are usually derived in the context of Young's double slit experiment, though they may actually be applied to a large number of other situations. The underlying assumptions upon which these equations are based are that two sources of coherent, nearly monochromatic light are available, and that their interference pattern is observed at a distance very large in comparison to the separation of the sources. Monochromatic means that the wavelengths of the waves, which determine color for visible light, are nearly identical. Coherent means that the waves are in phase when they leave the two sources. In Young's experiment, these two sources corresponded to the two slits (hence such phenomena are often called two-slit interference). Under these assumptions, the conditions for constructive and destructive interference are as follows: for constructive interference , and for destructive interference , where is the separation between the two sources, is the wavelength of the light, is an arbitrary integer, and is the angle between a line perpendicular to the line segment connecting the sources and the line from the midpoint of that segment to the point where the interference is being observed. These equations are often spoken of in terms of visible light, but they are, in fact, valid for any sort of waves, as long as the two sources fit the other criteria given. Part A Which of the following scenerios fits all of the criteria for the two-source interference equations to be valid? ANSWER: An observer is standing far away from two red signal lights. Light from an incandescent bulb shines onto a screen with a single slit; [ Print ] then the light shines onto a screen with two slits in it and the light from the two slits finally shines onto a far-away screen. An observer stands on a road far away from two neighboring radio towers for different radio stations. Light from an incandescent bulb shines onto a screen with a single slit; then the light shines onto a screen with two slits in it and the light from the two slits finally shines onto a nearby screen. An observer stands on a road that runs five kilometers away from the two synchronized transmitting towers for a radio station. ...

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