Michelson Interferometer?

Question

A Michelson interferometer is adjusted so that a bright fringe appears on the screen. As one of the mirrors is moved 26.1 m, 95 bright fringes are counted on the screen. What is the wavelength of the light used in the interferometer?

Can anyone help me with an equation? Thank you!!

Answer 1

lambda = 2d/n

micrometers was the given unit of measure

answer needs to be in nanometers though

Answer 2

The equation you need is:

d = n x lambda / 2

Where d is the distance and n the number of fringes counted when moving through this distance. You get:

lambda = 2d/n = 0.55 m

Of course this is a much too large wavelength for visible light. I guess you have a wrong unit for distance, I suppose it was given in micrometers, not meters. In that case, the result is 0.55 micrometers = 550 nanometers (green light).