Solving for Mirror Displacement in a Michelson Interferometer

[Ryoblck]

Homework Statement

The distance between the movable mirror and the beam splitter in a Michelson interferometer is increased a small amount. When this happens, you see 200 dark fringes move across the field of view. If the incident light was 600nm, by how much was the mirror moved (in millimeters)?

Homework Equations

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The Attempt at a Solution

My teacher has not taught me anything about Michelson interferometer. It not even in the book! I asked my tutor and he does not know how to solve the problem. He knew about Michelson but he doesn't know how to link it together to solve the problem.

 

[Simon Bridge]

You should ask your teacher or a classmate - you obviously missed a lesson.
Your tutor should have known enough to know where to find the relations you needed.
http://en.wikipedia.org/wiki/Michelson_interferometer
http://en.wikipedia.org/wiki/Michelson–Morley_experiment
(2nd one has math).

There are equivalent questions in PF too. eg.
https://www.physicsforums.com/showthread.php?t=558021

Considering how complex the theory looks - the actual equations are fairly straight forward.