GATE2016-3-52

Question

Two optically flat plates of glass are kept at a small angle $\theta$ as shown in the figure. Monochromatic light is incident vertically.

If the wavelength of light used to get a fringe spacing of $1$ $mm$ is $450$ $nm$, the wavelength of light (in $nm$) to get a fringe spacing of $1.5$ $mm$ is _________

Answer 1

N* lemda1 = 1mm

N =1/450

Again N *lemda2= 1.5

Lemda2= 1.5/N= 675