- #1

Cocoleia

- 295

- 4

## Homework Statement

In a Michelson interferometer, as one of the mirrors is moved, 250 bright fringes disappear into the centre. If the light wavelength was 800nm, how far was the mirror moved?

## Homework Equations

## The Attempt at a Solution

My logic is:

If we were to count how many passing bright fringes we have, we could find the wavelength, basing ourselves off of the formula: 2d=mλ. In this case I would say 2Δd=Δmλ, where Δd is the distance that the mirror moved and Δm is the number of passing bright fringes.

So I would solve for Δd and get 0.01cm

My problem is, I am pretty sure I need to somehow derive 2d=mλ, I can't just use it. Can someone get me started on how to derive this?

Also, is my logic correct