Light is incident normally on a diffraction grating through which first order diffraction is seen at 32°. The second order diffraction will be seen at
Answer & explanation
Correct answer: option 4
For second order diffraction,
$\sin θ_2=\frac{2λ}{d}=2\sin θ_1$
$= 2 \sin 32° > 1$
Which is not possible. Hence there is no second order diffraction.