Physics (AS & A Level) · May / June 2025 · Paper 14 · Question 27

Red light of a single wavelength from a laser is incident on a double slit. A pattern of interference fringes is observed on a flat screen that is placed parallel to the double slit. Which change increases the separation of the interference fringes on the screen?

1. ADecrease the distance from the double slit to the screen.
2. BDecrease the separation of the slits.
3. CReplace the red light with blue light.
4. DReplace the red light with green light.

As printed in the paper