Physics (AS & A Level) · May / June 2026 · Paper 13 · Question 29

Light of wavelength 400 nm passes normally through a diffraction grating with a line spacing of 2.0 × 10⁻⁶ m and forms a diffraction pattern on a screen. [diagram: diffraction grating, incident light ray, screen, second-order diffracted ray, fourth-order diffracted ray, angle α, not to scale] What is the angle α between the second-order and the fourth-order diffracted rays?

1. A24°
2. B30°
3. C53°
4. D77°

As printed in the paper