Question

A beam of 541nm light is incident on a diffraction grating that has 400grooves/mm. Determine the angle of the second-order ray.

Answer 1

Answer

Grid spacing

$d=\frac{10^{-3}}{400}=2.50\times10^{-6}m$

And by equation

$dsin\theta=m\lambda$

$\theta=sin^{-1}(\frac{m\lambda}{d})$

$\theta=sin^{-1}(\frac{(2)(541\times10^{-9})}{250\times10^{-6})}) \\\theta=25.6°$