Light composed of two spectral lines with wavelength `600.00` and `600.050nm` falls normally on a diffraction grating `10.0mm` wide. At a centain diffraction angle `theta` these lines are close to being resolved (according to Rayleigh's criterion). Find `theta`.

Explanation

`delta lambda = 0.50nm`
`R = (lambda)/(delta lambda) ~=(600)/(05) = 12000` (nearly)
On the other hand
`d sin theta = k lambda`
Thus `(l)/(kN)sin theta = lambda`
where `l = 10^(-2)` metre is the width of the grating
Hence `sintheta = 12000 xx (lambda)/(l)`
`= 12000 xx 600 xx 10^(-7) = 0.72`
or `theta = 46^(@)`.