1. The problem statement, all variables and given/known data A micrometer is connected to the movable mirror of an interferometer. When the micrometer bears on a thin metal foil, the net number of bright fringes that move, compared to the empty micrometer, is 272. What is the thickness of the foil? The wavelength of light used is 589 nm. I don't understand how to the micrometer is attached and what the metal foil does. Can someone tell me what it means in different words? Thanks. 2. Relevant equations Not sure until I figure out what the question is saying. 3. The attempt at a solution Not sure until I figure out what the question is saying.