Physics (AS & A Level) · Feb / March 2020 · Paper 12 · Question 29

Light of wavelength λ is incident normally on a diffraction grating, as shown. The angle between the two second-order maxima is φ. Which expression gives the spacing of the lines on the diffraction grating?

1. A\frac{\lambda}{\sin\varphi}
2. B\frac{\lambda}{\sin(\varphi/2)}
3. C\frac{2\lambda}{\sin\varphi}
4. D\frac{2\lambda}{\sin(\varphi/2)}

As printed in the paper