Physics (AS & A Level) · May / June 2021 · Paper 12 · Question 29

A parallel beam of light consists of light of wavelength 420 nm and light of wavelength 630 nm. The light is incident normally on a diffraction grating. The diffraction maxima for the two wavelengths overlap only at an angle of 31° from the direction of the incident light beam. What could be the line spacing of the diffraction grating?

1. A1.2 μm
2. B1.6 μm
3. C2.4 μm
4. D3.7 μm

As printed in the paper