# Movable mirror of a Michelson interferometer

1. Jan 5, 2010

### oaly

i know the question may be a bit stupid to some people, but i seriously don't know how to do it....
1. The problem statement, all variables and given/known data
How far must the movable mirror of a Michelson interferometer, illuminated by a 589-nm source, be displaces for 2000 fringes to move past the reference point?

2. Relevant equations

i have no idea

3. The attempt at a solution

i don't know how to solve it
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 5, 2010

### ideasrule

Re: interferometer

What's the path length difference associated with 2000 fringes?

3. Jan 6, 2010

### oaly

Re: interferometer

it does not say, that was the whole question.

4. Jan 6, 2010

### ideasrule

Re: interferometer

Yes, but it does tell you the wavelength, and constructive interference occurs when the path length difference is an integer multiple of the wavelength.

5. Feb 22, 2010

### bshweta

Re: interferometer