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 268. What is the thickness of the foil - in microns? The wave length of light used is 596 nm.
The answer is 79.9 microns, I wonder how to get this result
2006-08-09 03:55:13 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Physics
An interferometer uses light waves to compare the lengths of two different paths. The light waves will interfere constructively--creating a bright spot--when the paths are the same length or differ by a number of full wavelengths, while they will interfere destructively (dark spot) when the paths differ by an odd number of half-wavelengths. So the difference in path length corresponding to one bright-dark change is one half wavelength of whatever light you're using. As you dial the micrometer, you are changing one of the paths.
2006-08-09 06:20:49 · answer #1 · answered by Benjamin N 4 · 0⤊ 0⤋