Physics (AS & A Level) · May / June 2026 · Paper 13 · Question 28

A beam of white light is incident normally on a diffraction grating. Three bands of bright fringes are formed on a screen, labelled 1, 2 and 3 as shown. What are the colours of the fringes seen on the screen?

1. A1: continuous spectrum red → violet; 2: white; 3: continuous spectrum violet → red
2. B1: continuous spectrum violet → red; 2: white; 3: continuous spectrum red → violet
3. C1: continuous spectrum red → violet; 2: continuous spectrum red – violet – red; 3: continuous spectrum violet → red
4. D1: continuous spectrum violet → red; 2: continuous spectrum violet – red – violet; 3: continuous spectrum red → violet

As printed in the paper