The diffraction grating
8.4What the syllabus asks of you
- recall and use d sin θ = nλ
- describe the use of a diffraction grating to determine the wavelength of light (the structure and use of the spectrometer are not included)
Read the notes first
Chapter 8: The diffraction grating
Drill this topic
Every question on The diffraction grating, untimed, marked as you go.
Make a worksheet
Choose the years and how many questions, then print it with the answers on separate pages.
64 questions
1May / June 2026 · Paper 12 · Q27Show mark scheme →
A0.25
B0.75
C1.25
D1.50
Mark scheme
2May / June 2026 · Paper 13 · Q28Show mark scheme →
A1: continuous spectrum red → violet; 2: white; 3: continuous spectrum violet → red
B1: continuous spectrum violet → red; 2: white; 3: continuous spectrum red → violet
C1: continuous spectrum red → violet; 2: continuous spectrum red – violet – red; 3: continuous spectrum violet → red
D1: continuous spectrum violet → red; 2: continuous spectrum violet – red – violet; 3: continuous spectrum red → violet
Mark scheme
3May / June 2026 · Paper 13 · Q29Show mark scheme →
A24°
B30°
C53°
D77°
Mark scheme
4Oct / Nov 2025 · Paper 11 · Q30Show mark scheme →
A4
B5
C8
D9
Mark scheme
5Oct / Nov 2025 · Paper 12 · Q29Show mark scheme →
Ad — distance from grating to screen
Bλ — wavelength of light
Cn — order of intensity maximum
Dθ — diffraction angle of intensity maximum
Mark scheme
6Oct / Nov 2025 · Paper 13 · Q30Show mark scheme →
A4
B5
C8
D9
Mark scheme
7Oct / Nov 2025 · Paper 14 · Q30Show mark scheme →
A6
B7
C8
D9
Mark scheme
8May / June 2025 · Paper 11 · Q30Show mark scheme →
A1.8°
B3.5°
C18°
D38°
Mark scheme
9May / June 2025 · Paper 12 · Q29Show mark scheme →
A3 × 10^5 G
B3.3 × 10^–6 G
C3.3 × 10^–6 / G
D300 / G
Mark scheme
10May / June 2025 · Paper 14 · Q28Show mark scheme →
A2.5 × 10⁻⁷ m
B5.0 × 10⁻⁷ m
C1.0 × 10⁻⁶ m
D5.0 × 10⁻⁵ m
Mark scheme
11Feb / March 2025 · Paper 12 · Q29Show mark scheme →
A13.1°
B13.9°
C15.9°
D27.0°
Mark scheme
12Oct / Nov 2024 · Paper 11 · Q30Show mark scheme →
A\frac{w\lambda}{\sin\theta}
B\frac{2w\lambda}{\sin\theta}
C\frac{w\sin\theta}{2\lambda}
D\frac{w\sin\theta}{\lambda}
Mark scheme
13Oct / Nov 2024 · Paper 12 · Q30Show mark scheme →
A4.1 × 10⁻⁷ m
B5.4 × 10⁻⁷ m
C1.6 × 10⁻⁶ m
D2.2 × 10⁻⁶ m
Mark scheme
14May / June 2024 · Paper 11 · Q26Show mark scheme →
A12°
B21°
C33°
D54°
Mark scheme
15May / June 2024 · Paper 12 · Q26Show mark scheme →
ANn
BN/n
Cn/N
D1/(Nn)
Mark scheme
16May / June 2024 · Paper 13 · Q29Show mark scheme →
A2.25 × 10⁻⁶ m
B2.80 × 10⁻⁶ m
C4.40 × 10⁻⁶ m
D4.95 × 10⁻⁶ m
Mark scheme
17Oct / Nov 2023 · Paper 11 · Q29Show mark scheme →
A480 nm
B540 nm
C960 nm
D1100 nm
Mark scheme
18Oct / Nov 2023 · Paper 12 · Q29Show mark scheme →
A4
B5
C8
D9
Mark scheme
19Oct / Nov 2023 · Paper 13 · Q29Show mark scheme →
A288 nm
B498 nm
C575 nm
D996 nm
Mark scheme
20May / June 2023 · Paper 11 · Q29Show mark scheme →
A4.1 × 10⁻⁷ m
B4.7 × 10⁻⁷ m
C8.2 × 10⁻⁷ m
D9.4 × 10⁻⁷ m
Mark scheme
21May / June 2023 · Paper 12 · Q29Show mark scheme →
A2.6 \times 10^{-6}\ \text{m}
B7.7 \times 10^{-6}\ \text{m}
C7.9 \times 10^{-6}\ \text{m}
D1.0 \times 10^{-5}\ \text{m}
Mark scheme
22May / June 2023 · Paper 13 · Q29Show mark scheme →
A1.4 m
B2.7 m
C3.1 m
D6.2 m
Mark scheme
23Feb / March 2023 · Paper 12 · Q29Show mark scheme →
Ad ✓, λ ✓, L ✓, N ✗
Bd ✓, λ ✓, L ✗, N ✗
Cd ✓, λ ✗, L ✓, N ✓
Dd ✗, λ ✓, L ✗, N ✓
Mark scheme
24Oct / Nov 2022 · Paper 11 · Q30Show mark scheme →
A13.6°
B27.3°
C28.1°
D56.2°
Mark scheme
25Oct / Nov 2022 · Paper 12 · Q30Show mark scheme →
ASeven evenly spaced small dots
BThree evenly spaced small dots
CCentral small dot with elongated coloured bands on either side
DCentral small dot with elongated coloured bands on either side (wider spacing)
Mark scheme
26Oct / Nov 2022 · Paper 13 · Q29Show mark scheme →
Aamplitude
Bintensity
Cspeed
Dwavelength
Mark scheme
27May / June 2022 · Paper 11 · Q30Show mark scheme →
A3
B4
C6
D7
Mark scheme
28May / June 2022 · Paper 12 · Q30Show mark scheme →
An: number of slits in the grating; d: distance between adjacent slits in the grating
Bn: number of slits in the grating; d: distance from grating to screen
Cn: order of intensity maximum; d: distance between adjacent slits in the grating
Dn: order of intensity maximum; d: distance from grating to screen
Mark scheme
29May / June 2022 · Paper 13 · Q31Show mark scheme →
A8
B9
C16
D17
Mark scheme
30Feb / March 2022 · Paper 12 · Q28Show mark scheme →
Aplacing the screen closer to the diffraction grating
Busing a diffraction grating with less separation between adjacent slits
Cusing a diffraction grating with more slits but keeping the same separation between adjacent slits
Dusing light with a shorter wavelength
Mark scheme
31Oct / Nov 2021 · Paper 11 · Q29Show mark scheme →
AIncrease the distance between the screen and the diffraction grating.
BReplace the diffraction grating with a grating that has a smaller separation between the slits.
CReplace the diffraction grating with a grating that has fewer slits per unit length.
DReplace the green light with red light.
Mark scheme
32Oct / Nov 2021 · Paper 12 · Q30Show mark scheme →
A5.8 × 10⁵ lines per metre
B9.0 × 10⁵ lines per metre
C1.2 × 10⁶ lines per metre
D2.3 × 10⁶ lines per metre
Mark scheme
33Oct / Nov 2021 · Paper 13 · Q30Show mark scheme →
AUse blue light and increase the distance between the grating and the screen.
BUse blue light and increase the number of lines per unit length in the grating.
CUse red light and increase the distance between the grating and the screen.
DUse red light and increase the number of lines per unit length in the grating.
Mark scheme
34May / June 2021 · Paper 11 · Q29Show mark scheme →
A320 nm
B720 nm
C960 nm
D1440 nm
Mark scheme
35May / June 2021 · Paper 12 · Q29Show mark scheme →
A1.2 μm
B1.6 μm
C2.4 μm
D3.7 μm
Mark scheme
36May / June 2021 · Paper 13 · Q30Show mark scheme →
Ay-axis: n, x-axis: d sin θ, wavelength: gradient
By-axis: n, x-axis: d sin θ, wavelength: 1 / gradient
Cy-axis: sin θ, x-axis: d / n, wavelength: gradient
Dy-axis: sin θ, x-axis: d × n, wavelength: 1 / gradient
Mark scheme
37Feb / March 2021 · Paper 12 · Q29Show mark scheme →
A420 mm⁻¹
B470 mm⁻¹
C600 mm⁻¹
D850 mm⁻¹
Mark scheme
38Oct / Nov 2020 · Paper 11 · Q29Show mark scheme →
A450 nm
B480 nm
C500 nm
D750 nm
Mark scheme
39Oct / Nov 2020 · Paper 12 · Q30Show mark scheme →
AIncrease the distance between the grating and the screen.
BIncrease the frequency of the incident light.
CIncrease the intensity of the incident light.
DIncrease the number of lines per metre in the grating.
Mark scheme
40Oct / Nov 2020 · Paper 13 · Q30Show mark scheme →
A$7.7^\circ$
B$15.4^\circ$
C$16.7^\circ$
D$32.1^\circ$
Mark scheme
41May / June 2020 · Paper 11 · Q30Show mark scheme →
AA curved screen must be used.
BThe diffraction angle θ must be measured for at least two interference maxima.
CThe light waves incident on the grating must be coherent.
DThe third order intensity maximum must be produced.
Mark scheme
42May / June 2020 · Paper 12 · Q30Show mark scheme →
A400 mm⁻¹
B625 mm⁻¹
C800 mm⁻¹
D1250 mm⁻¹
Mark scheme
43May / June 2020 · Paper 13 · Q30Show mark scheme →
Aa central point source with a series of point source images on either side
Ba central vertical line with a series of spectra on either side
Ca series of fine vertical lines
Da single point source
Mark scheme
44Feb / March 2020 · Paper 12 · Q29Show mark scheme →
A\frac{\lambda}{\sin\varphi}
B\frac{\lambda}{\sin(\varphi/2)}
C\frac{2\lambda}{\sin\varphi}
D\frac{2\lambda}{\sin(\varphi/2)}
Mark scheme
45Oct / Nov 2019 · Paper 11 · Q28Show mark scheme →
A480 nm
B540 nm
C720 nm
D1080 nm
Mark scheme
46Oct / Nov 2019 · Paper 11 · Q29Show mark scheme →
An = cf/d
Bn = c/(df)
Cn = f/(dc)
Dn = df/c
Mark scheme
47Oct / Nov 2019 · Paper 12 · Q28Show mark scheme →
A2.5 × 10⁻⁷ m
B5.0 × 10⁻⁷ m
C1.0 × 10⁻⁶ m
D5.0 × 10⁻⁵ m
Mark scheme
48Oct / Nov 2019 · Paper 13 · Q30Show mark scheme →
A13.1°
B13.9°
C15.9°
D27.0°
Mark scheme
49May / June 2019 · Paper 11 · Q30Show mark scheme →
A2.5 × 10⁻⁷ m
B1.0 × 10⁻⁵ m
C1.0 × 10⁻³ m
D1.0 × 10⁻¹ m
Mark scheme
50May / June 2019 · Paper 12 · Q29Show mark scheme →
ADiagram A
BDiagram B
CDiagram C
DDiagram D
Mark scheme
51May / June 2019 · Paper 13 · Q30Show mark scheme →
A4
B5
C8
D9
Mark scheme
52Feb / March 2019 · Paper 12 · Q29Show mark scheme →
A17.5°
B19.4°
C36.9°
D54.3°
Mark scheme
53Oct / Nov 2018 · Paper 11 · Q29Show mark scheme →
A19.1°
B25.8°
C40.8°
D78.8°
Mark scheme
54Oct / Nov 2018 · Paper 12 · Q30Show mark scheme →
A2λ / sin α
Bλ / sin α
C2λ / sin(α/2)
Dλ / sin(α/2)
Mark scheme
55Oct / Nov 2018 · Paper 13 · Q29Show mark scheme →
A300 nm
B400 nm
C600 nm
D900 nm
Mark scheme
56Oct / Nov 2017 · Paper 11 · Q30Show mark scheme →
A287 nm
B470 nm
C574 nm
D940 nm
Mark scheme
57May / June 2017 · Paper 11 · Q28Show mark scheme →
A1
B3
C11
D13
Mark scheme
58May / June 2017 · Paper 12 · Q28Show mark scheme →
A6
B7
C8
D9
Mark scheme
59May / June 2017 · Paper 13 · Q27Show mark scheme →
Anumber of orders of diffraction visible: decreases; angle between first and second orders of diffraction: decreases
Bnumber of orders of diffraction visible: decreases; angle between first and second orders of diffraction: increases
Cnumber of orders of diffraction visible: increases; angle between first and second orders of diffraction: decreases
Dnumber of orders of diffraction visible: increases; angle between first and second orders of diffraction: increases
Mark scheme
60Oct / Nov 2016 · Paper 11 · Q29Show mark scheme →
A288 nm
B498 nm
C575 nm
D996 nm
Mark scheme
61Oct / Nov 2016 · Paper 13 · Q29Show mark scheme →
A288 nm
B498 nm
C575 nm
D996 nm
Mark scheme
62May / June 2016 · Paper 11 · Q26Show mark scheme →
A7
B8
C14
D15
Mark scheme
63May / June 2016 · Paper 13 · Q27Show mark scheme →
ANn
BN/n
Cn/N
D1/(Nn)
Mark scheme
64Feb / March 2016 · Paper 12 · Q26Show mark scheme →
A7.7°
B15.4°
C16.7°
D32.1°
Mark scheme