Question

light of wavelength 589.3nm falls normally on a plane transmission grating having 600 lines/cm. calculate the angle at which the principal maxima of the first order form

Answer 1

$d\sin\theta=m\lambda$

$d=\frac{0.01}{600}=1.67\cdot10^{-5}\ (m)$

$\theta=\sin^{-1}(m\lambda/d)=\sin^{-1}(1\cdot589.3\cdot10^{-9}/1.67\cdot10^{-5})\approx2°$ . Answer