Physics (AS & A Level) · May / June 2026 · Paper 12 · Question 27

The diagram shows a beam of light of wavelength \lambda_X that is incident normally on a diffraction grating. The diagram shows only the second-order intensity maxima that are produced at an angle of 45° to the direction of the incident beam of light. A replacement beam of light of a different wavelength \lambda_Y is now incident normally on the diffraction grating. This new wavelength also produces intensity maxima that are at an angle of 45° to the direction of the incident beam of light. What is a possible value of the ratio \frac{\lambda_X}{\lambda_Y}?

1. A0.25
2. B0.75
3. C1.25
4. D1.50

As printed in the paper