Thin Film Interference

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Thin Film Interference

• Use Polarizing Film
• Plastic Wrap

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Stolen (on short notice) from Wikipedia.com
http//en.wikipedia.org/wiki/Thin-film_interferen
ce

• Oil film, Soap Bubbles, or plastic film
• Light incident on an oil film. Air is at the
  upper boundary and water at the lower boundary.
• In the case of a thin oil (etc.) film, a layer of
  oil sits atop a layer of water. The oil may have
  an index of refraction near 1.5 and the water has
  an index of 1.33. As in the case of the soap
  bubble, the materials on either side of the oil
  film (air and water) both have refractive indices
  that are less than the index of the film. Or nair
  lt nwater lt noil. There will be a phase shift upon
  reflection from the upper boundary because nair lt
  noil but no shift upon reflection from the lower
  boundary because noil gt nwater. The equations for
  interference will be the same.
• 2nfilm d cos ?2 (m ½)?   for constructive
  interference of reflected light.
• 2nfilm d cos ?2 m? for destructive
  interference of reflected light.