26.19. Set Up: Consider light reflected at the front and rear surfaces of the film. At the front surface of the film, light in air reflects from the film and there is a phase shift due to the reflection. At the back surface of the film, light in the film reflects from glass and there is no phase shift due to reflection. Therefore, there is a net phase difference produced by the reflections. The path difference for these two rays is 2 t , where t is the thickness of the film. The wavelength in the film is Solve: (a) Since the reflection produces a net phase difference, destructive interference of the reflected light occurs when The minimum thickness is 96.4 nm. (b) The next three thicknesses are for 3 and 4: 192 nm, 289 nm and 386 nm. Reflect: The minimum thickness is for Compare this to Problem 26.15, where the minimum thickness for destructive interference is 26.20. Set Up: The path length is The wavelength in the film is Solve: The number of waves is 26.21. Set Up: The fringes are produced by interference between light reflected from the top and from the bottom
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This note was uploaded on 03/06/2009 for the course PHYS 114 taught by Professor Shoberg during the Spring '07 term at Pittsburg State Uiversity.