Physics 9702 · AS & A Level · The diffraction grating

The diffraction grating — practice question

(a)[2]

Describe how monochromatic light diffracts as it goes through a diffraction grating.

(b(i).1)[2]

White light is incident on a diffraction grating, as shown in Fig. 4.1. Describe, using the principle of superposition, how white light at the zero order is explained.

(b(i).2)[2]

Describe how the principle of superposition explains why red and blue light appear at different positions in the first-order spectrum.

(b(ii))[2]

A light wave with wavelength $625\\,\\text{nm}$ gives a second-order maximum at $61.0^\\circ$ to the incident direction. Determine the number of lines per metre of the diffraction grating.

(b(iii))[2]

Calculate the wavelength of another visible part of the spectrum that gives a maximum in a different order at the same angle as in (ii).

(ii)[2]

A light wave of wavelength $625\\,\\text{nm}$ gives a second-order maximum at an angle of $61.0^\\circ$ to the incident direction. Determine the number of lines per metre of the diffraction grating.

(iii)[2]

Calculate the wavelength of another visible part of the spectrum that produces a maximum for a different order at the same angle as in (ii).

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: waves travel through the elements / gaps / slits of the grating

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI