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Unformatted text preview: 26.56. Set Up: Consider the interference of the rays reflected from each side of the film. At the front of the film light in air reflects off the film and there is a phase shift. At the back of the film light in the film reflects off the glass and there is a phase shift. Therefore, the reflections introduce no net phase shift. The path difference 2 t , where t is the thickness of the film. The wavelength in the film is Solve: (a) Since there is no net phase difference produced by the reflections, the condition for destructive interfer- ence is and the minimum thickness is (b) For destructive interference, and All other values are shorter. The only visible wavelength in air for which there is destructive inter- ference is 550 nm. For constructive interference, and For and all other values are shorter. There are no visible wavelengths in air for which there is constructive interference. 26.57. Set Up: The two sheets of glass are sketched in Figure 26.57. The thickness of the air wedge at a distance The two sheets of glass are sketched in Figure 26....
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- Spring '07