Physics (AS & A Level) · Oct / Nov 2020 · Paper 13 · Question 29

In a dark room, a small source of red light illuminates two slits that are 0.75 mm apart. A few metres beyond the slits, the light falls on a screen producing a series of equally spaced bright lines. Which change would cause the distance between the bright lines on the screen to be reduced?

1. AChange the source for one emitting blue light.
2. BReduce the distance between the light source and the slits.
3. CReduce the distance between the slits to 0.55 mm.
4. DReduce the intensity of the light source.

As printed in the paper