Physics (AS & A Level) · May / June 2021 · Paper 13 · Question 30

A beam of light of a single wavelength is incident normally on a diffraction grating. The angle of diffraction θ is measured for each order of diffraction n. The distance between adjacent slits in the diffraction grating is d. A graph is plotted to determine the wavelength of the light. Which graph should be plotted and how is the wavelength determined from the graph?

1. Ay-axis: n, x-axis: d sin θ, wavelength: gradient
2. By-axis: n, x-axis: d sin θ, wavelength: 1 / gradient
3. Cy-axis: sin θ, x-axis: d / n, wavelength: gradient
4. Dy-axis: sin θ, x-axis: d × n, wavelength: 1 / gradient

As printed in the paper