Question

In an experiment with Michelson's Interferometer 99 fringes cross the field of view when the movable mirror is displaced through 0.02759 mm. Calculate the wavelength of manochromatic light used.

Answer 1

Number of fringes, $n=99$

Width of slit, $d=0.02759\space mm=0.02759\times10^{-3}\space m$

Wavelength, $\lambda=\dfrac{2d}{n}=\dfrac{2\times0.02759\times10^{-3}}{99}=5.57\times10^{-7}\space m$