Unformatted text preview: Solve: Since the reflections introduce a net phase difference, the condition for destructive interference is so The separation between adjacent dark fringes is and 26.59. Set Up: Consider reflection from either side of the film. (a) 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 cornea and there is no phase shift. The reflections produce a net phase difference and the condition for constructive interference is where Minimum thickness is for and is given by (b) For For and all other values are smaller. No other visible wavelengths are reinforced. The condition for destructive interference is For and all other values are shorter. There are no visible wavelengths for which there is destructive interference. (c) Now both rays have a phase change on reflection and the reflections don’t introduce any net phase shift. The expression for constructive interference in parts (a) and (b) now gives destructive interference and the expression in...
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- Spring '07
- Diffraction, Wavelength, Visible spectrum