Doppler effect for sound waves
7.3What the syllabus asks of you
- understand that when a source of sound waves moves relative to a stationary observer, the observed frequency is different from the source frequency (understanding of the Doppler effect for a stationary source and a moving observer is not required)
- use the expression fo = fs v / (v ± vs) for the observed frequency when a source of sound waves moves relative to a stationary observer
Read the notes first
Chapter 7: Doppler effect for sound waves
Drill this topic
Every question on Doppler effect for sound waves, untimed, marked as you go.
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Choose the years and how many questions, then print it with the answers on separate pages.
76 questions
1May / June 2026 · Paper 11 · Q24Show mark scheme →
Agraph A
Bgraph B
Cgraph C
Dgraph D
Mark scheme
2May / June 2026 · Paper 12 · Q24Show mark scheme →
A31 m s⁻¹ away from the stationary car
B34 m s⁻¹ away from the stationary car
C31 m s⁻¹ towards the stationary car
D34 m s⁻¹ towards the stationary car
Mark scheme
3May / June 2026 · Paper 13 · Q24Show mark scheme →
Aaway from observer, 10 m s–1
Baway from observer, 5 m s–1
Ctowards observer, 10 m s–1
Dtowards observer, 5 m s–1
Mark scheme
4May / June 2026 · Paper 14 · Q23Show mark scheme →
A268 Hz
B300 Hz
C335 Hz
D340 Hz
Mark scheme
5Oct / Nov 2025 · Paper 11 · Q27Show mark scheme →
A1300 Hz
B1330 Hz
C121 kHz
D123 kHz
Mark scheme
6Oct / Nov 2025 · Paper 12 · Q27Show mark scheme →
A68 m s⁻¹ directly away from the observer
B68 m s⁻¹ directly towards the observer
C85 m s⁻¹ directly away from the observer
D85 m s⁻¹ directly towards the observer
Mark scheme
7Oct / Nov 2025 · Paper 13 · Q27Show mark scheme →
A1300 Hz
B1330 Hz
C121 kHz
D123 kHz
Mark scheme
8Oct / Nov 2025 · Paper 14 · Q27Show mark scheme →
A2(v + v_s)
B\frac{v + v_s}{2}
C2v_s + v
D2v_s - v
Mark scheme
9May / June 2025 · Paper 11 · Q24Show mark scheme →
A110, away from observer
B110, towards observer
C165, away from observer
D165, towards observer
Mark scheme
10May / June 2025 · Paper 12 · Q26Show mark scheme →
A783 Hz
B788 Hz
C908 Hz
D913 Hz
Mark scheme
11May / June 2025 · Paper 14 · Q22Show mark scheme →
A401 Hz
B404 Hz
C479 Hz
D483 Hz
Mark scheme
12Feb / March 2025 · Paper 12 · Q24Show mark scheme →
A1, 2 and 3
B1 and 2 only
C3 only
Dnone of them
Mark scheme
13Oct / Nov 2024 · Paper 12 · Q26Show mark scheme →
Aspeed 5 m s⁻¹, away from observer
Bspeed 10 m s⁻¹, away from observer
Cspeed 15 m s⁻¹, towards observer
Dspeed 20 m s⁻¹, towards observer
Mark scheme
14Oct / Nov 2024 · Paper 13 · Q24Show mark scheme →
Aobserver and source, source moving away at 5 m s⁻¹
Bobserver and source, source moving away at 10 m s⁻¹
Cobserver and source, source moving towards at 5 m s⁻¹
Dobserver and source, source moving towards at 10 m s⁻¹
Mark scheme
15May / June 2024 · Paper 11 · Q27Show mark scheme →
A37 m s⁻¹ directly away from the observer
B37 m s⁻¹ directly towards the observer
C42 m s⁻¹ directly away from the observer
D42 m s⁻¹ directly towards the observer
Mark scheme
16May / June 2024 · Paper 12 · Q21Show mark scheme →
Awhen the swing is at X
Bwhen the swing is at Y and moving away from the man
Cwhen the swing is at Y and moving towards the man
Dwhen the swing is at Z
Mark scheme
17May / June 2024 · Paper 13 · Q24Show mark scheme →
Aequal to f and decreasing
Bequal to f and increasing
Cgreater than f and constant
Dless than f and constant
Mark scheme
18Feb / March 2024 · Paper 12 · Q26Show mark scheme →
Aa decreased frequency of the sound waves
Bno change in frequency of the sound waves
Ca decreased wavelength of the sound waves
Dno change in wavelength of the sound waves
Mark scheme
19Oct / Nov 2023 · Paper 11 · Q22Show mark scheme →
Amagnitude of velocity 19 m s⁻¹, direction away from the observer
Bmagnitude of velocity 21 m s⁻¹, direction away from the observer
Cmagnitude of velocity 19 m s⁻¹, direction towards the observer
Dmagnitude of velocity 21 m s⁻¹, direction towards the observer
Mark scheme
20Oct / Nov 2023 · Paper 12 · Q22Show mark scheme →
A89 m s⁻¹
B120 m s⁻¹
C250 m s⁻¹
D340 m s⁻¹
Mark scheme
21Oct / Nov 2023 · Paper 13 · Q22Show mark scheme →
Aa frequency greater than f_s and increasing
Ba frequency greater than f_s but decreasing
Ca frequency less than f_s and decreasing
Da frequency less than f_s but increasing
Mark scheme
22May / June 2023 · Paper 11 · Q22Show mark scheme →
Aa frequency less than f that decreases as the car moves from P towards Q
Ba frequency less than f that increases as the car moves from P towards Q
Ca frequency more than f that decreases as the car moves from P towards Q
Da frequency more than f that increases as the car moves from P towards Q
Mark scheme
23May / June 2023 · Paper 12 · Q22Show mark scheme →
ABetween X and Y, the wave undergoes diffraction.
BBetween X and Y, the wave undergoes reflection.
CX is moving away from Y.
DX is moving towards Y.
Mark scheme
24May / June 2023 · Paper 13 · Q22Show mark scheme →
Adiffraction
Binterference
Cpolarisation
Dthe Doppler effect
Mark scheme
25Feb / March 2023 · Paper 12 · Q22Show mark scheme →
AThe source is moving away from the observer.
BThe source is moving towards the observer.
CThe speed of the sound wave in air decreases due to the movement of the source.
DThe speed of the sound wave in air increases due to the movement of the source.
Mark scheme
26Oct / Nov 2022 · Paper 11 · Q24Show mark scheme →
A56 Hz
B180 Hz
C400 Hz
D500 Hz
Mark scheme
27Oct / Nov 2022 · Paper 12 · Q24Show mark scheme →
A246 Hz
B249 Hz
C267 Hz
D313 Hz
Mark scheme
28Oct / Nov 2022 · Paper 13 · Q23Show mark scheme →
Asound of a decreasing frequency as the train approaches and of an increasing frequency as it moves away
Bsound of a higher frequency than f as the train approaches and of a lower frequency than f as the train moves away
Csound of a lower frequency than f as the train approaches and of a higher frequency than f as the train moves away
Dsound of an increasing frequency as the train approaches and as it moves away
Mark scheme
29May / June 2022 · Paper 11 · Q24Show mark scheme →
AThe frequency of the sound emitted by the horn is greater than the frequency of the sound heard by the man.
BThe frequency of the sound heard by the man depends on the distance between the car and the man.
CThe sound waves continually accelerate as they move from the horn to the man.
DThe wavelength of the sound heard by the man is less than the wavelength of the sound emitted by the horn.
Mark scheme
30May / June 2022 · Paper 12 · Q24Show mark scheme →
Aa source that is moving as it produces the sound wave
Ba source that produces a polarised sound wave
Ca source that produces a sound wave of changing amplitude
Da source that produces a sound wave of changing frequency
Mark scheme
31May / June 2022 · Paper 13 · Q25Show mark scheme →
A51 Hz
B69 Hz
C350 Hz
D470 Hz
Mark scheme
32Feb / March 2022 · Paper 12 · Q22Show mark scheme →
A49 Hz
B84 Hz
C91 Hz
D98 Hz
Mark scheme
33Oct / Nov 2021 · Paper 11 · Q24Show mark scheme →
Aall waves including sound and light
Blight waves only
Csound and light waves only
Dsound waves only
Mark scheme
34Oct / Nov 2021 · Paper 12 · Q25Show mark scheme →
A190 Hz
B230 Hz
C430 Hz
D460 Hz
Mark scheme
35Oct / Nov 2021 · Paper 13 · Q25Show mark scheme →
A34, away from the person
B34, towards the person
C38, away from the person
D38, towards the person
Mark scheme
36May / June 2021 · Paper 11 · Q24Show mark scheme →
Aapproaching observer: decreases; moving away from observer: decreases
Bapproaching observer: decreases; moving away from observer: increases
Capproaching observer: increases; moving away from observer: decreases
Dapproaching observer: increases; moving away from observer: increases
Mark scheme
37May / June 2021 · Paper 12 · Q24Show mark scheme →
A20 m s⁻¹
B38 m s⁻¹
C41 m s⁻¹
D43 m s⁻¹
Mark scheme
38May / June 2021 · Paper 13 · Q25Show mark scheme →
A29 Hz
B32 Hz
C40 Hz
D61 Hz
Mark scheme
39Feb / March 2021 · Paper 12 · Q24Show mark scheme →
A<F, <F
B<F, >F
C>F, <F
D>F, >F
Mark scheme
40Oct / Nov 2020 · Paper 11 · Q24Show mark scheme →
A110 m s⁻¹
B165 m s⁻¹
C220 m s⁻¹
D330 m s⁻¹
Mark scheme
41Oct / Nov 2020 · Paper 12 · Q25Show mark scheme →
Asound heard by person at X: higher than 750 Hz, increasing in frequency; sound heard by person at Y: lower than 750 Hz, decreasing in frequency
Bsound heard by person at X: higher than 750 Hz, decreasing in frequency; sound heard by person at Y: lower than 750 Hz, increasing in frequency
Csound heard by person at X: lower than 750 Hz, decreasing in frequency; sound heard by person at Y: higher than 750 Hz, increasing in frequency
Dsound heard by person at X: lower than 750 Hz, increasing in frequency; sound heard by person at Y: higher than 750 Hz, decreasing in frequency
Mark scheme
42Oct / Nov 2020 · Paper 13 · Q25Show mark scheme →
A0.80/1
B1/1.2
C1.2/1
D1/0.80
Mark scheme
43May / June 2020 · Paper 11 · Q25Show mark scheme →
AGraph A: $f_o$ constant below $f_s$, then steps up to constant above $f_s$
BGraph B: $f_o$ constant above $f_s$, then steps down to constant below $f_s$
CGraph C: $f_o$ increases linearly from below $f_s$ to above $f_s$
DGraph D: $f_o$ decreases linearly from above $f_s$ to below $f_s$
Mark scheme
44May / June 2020 · Paper 12 · Q25Show mark scheme →
Alonger / greater
Bshorter / greater
Clonger / same
Dshorter / same
Mark scheme
45May / June 2020 · Paper 13 · Q25Show mark scheme →
AThe frequency of the source S and the observed frequency are now both higher than f.
BThe frequency of the source S and the observed frequency are now both lower than f.
CThe frequency of the source S is now lower than f.
DThe observed frequency is now lower than f.
Mark scheme
46Feb / March 2020 · Paper 12 · Q24Show mark scheme →
A330 Hz
B667 Hz
C1000 Hz
D2000 Hz
Mark scheme
47Oct / Nov 2019 · Paper 11 · Q24Show mark scheme →
A37 m s–1 directly towards the observer
B37 m s–1 directly away from the observer
C42 m s–1 directly towards the observer
D42 m s–1 directly away from the observer
Mark scheme
48Oct / Nov 2019 · Paper 12 · Q23Show mark scheme →
A294 m s–1
B309 m s–1
C324 m s–1
D330 m s–1
Mark scheme
49Oct / Nov 2019 · Paper 13 · Q24Show mark scheme →
A\frac{1000 \times 330}{330 + 20}
B\frac{1000 \times 330}{330 - 20}
C\frac{1000(330 + 20)}{330}
D\frac{1000(330 - 20)}{330}
Mark scheme
50May / June 2019 · Paper 11 · Q25Show mark scheme →
Afrequency decreases; wave speed increases
Bfrequency decreases; wave speed stays the same
Cfrequency increases; wave speed increases
Dfrequency increases; wave speed stays the same
Mark scheme
51May / June 2019 · Paper 11 · Q26Show mark scheme →
A0.50 m s–1, directly away from the man
B0.50 m s–1, directly towards the man
C0.75 m s–1, directly away from the man
D0.75 m s–1, directly towards the man
Mark scheme
52May / June 2019 · Paper 12 · Q26Show mark scheme →
A15.4 m s⁻¹
B16.2 m s⁻¹
C17.0 m s⁻¹
D17.9 m s⁻¹
Mark scheme
53May / June 2019 · Paper 13 · Q24Show mark scheme →
A0.15 Hz
B0.16 Hz
C0.25 Hz
D0.27 Hz
Mark scheme
54Feb / March 2019 · Paper 12 · Q25Show mark scheme →
A783 Hz
B788 Hz
C908 Hz
D913 Hz
Mark scheme
55Oct / Nov 2018 · Paper 11 · Q24Show mark scheme →
A56 Hz
B180 Hz
C400 Hz
D500 Hz
Mark scheme
56Oct / Nov 2018 · Paper 12 · Q25Show mark scheme →
A268 Hz
B300 Hz
C335 Hz
D340 Hz
Mark scheme
57Oct / Nov 2018 · Paper 13 · Q24Show mark scheme →
A37.0 kHz
B37.2 kHz
C43.0 kHz
D43.3 kHz
Mark scheme
58May / June 2018 · Paper 11 · Q24Show mark scheme →
Adecreases, decreases
Bdecreases, increases
Cincreases, decreases
Dincreases, increases
Mark scheme
59May / June 2018 · Paper 13 · Q23Show mark scheme →
A1840 Hz
B2000 Hz
C2180 Hz
D2190 Hz
Mark scheme
60Feb / March 2018 · Paper 12 · Q24Show mark scheme →
AThe observed frequency will fall, then remain steady then return to the frequency F₀.
BThe observed frequency will fall, then remain steady then rise to a higher frequency than F₀.
CThe observed frequency will rise, then remain steady then fall to a lower frequency than F₀.
DThe observed frequency will rise, then remain steady then return to the frequency F₀.
Mark scheme
61Oct / Nov 2017 · Paper 11 · Q25Show mark scheme →
AThe Sun is moving at right-angles to a line joining the Sun and the Earth.
BThe Sun is moving away from the Earth.
CThe Sun is moving towards the Earth.
DThe Sun is rotating.
Mark scheme
62Oct / Nov 2017 · Paper 12 · Q25Show mark scheme →
A51 m s⁻¹ away from the woman
B51 m s⁻¹ towards the woman
C60 m s⁻¹ away from the woman
D60 m s⁻¹ towards the woman
Mark scheme
63Oct / Nov 2017 · Paper 13 · Q25Show mark scheme →
A<F, <F
B<F, >F
C>F, <F
D>F, >F
Mark scheme
64Oct / Nov 2017 · Paper 13 · Q26Show mark scheme →
A8.5 m s–1
B31 m s–1
C34 m s–1
D38 m s–1
Mark scheme
65May / June 2017 · Paper 11 · Q25Show mark scheme →
A39 Hz
B66 Hz
C72 Hz
D78 Hz
Mark scheme
66May / June 2017 · Paper 12 · Q25Show mark scheme →
Atowards man: 1820 Hz; away from man: 2180 Hz
Btowards man: 1840 Hz; away from man: 2190 Hz
Ctowards man: 2180 Hz; away from man: 1820 Hz
Dtowards man: 2190 Hz; away from man: 1840 Hz
Mark scheme
67May / June 2017 · Paper 13 · Q24Show mark scheme →
A190 Hz
B200 Hz
C310 Hz
D330 Hz
Mark scheme
68Feb / March 2017 · Paper 12 · Q23Show mark scheme →
ABoth light waves and sound waves show the Doppler effect.
BLight waves can be diffracted but sound waves cannot be diffracted.
CSound waves are transverse waves and light waves are longitudinal waves.
DSound waves can travel in a vacuum but light waves cannot travel in a vacuum.
Mark scheme
69Feb / March 2017 · Paper 12 · Q25Show mark scheme →
Aobserver and source, source moving left at 5 m s⁻¹
Bobserver and source, source moving left at 10 m s⁻¹
Cobserver and source, source moving right at 5 m s⁻¹
Dobserver and source, source moving right at 10 m s⁻¹
Mark scheme
70Oct / Nov 2016 · Paper 11 · Q26Show mark scheme →
A49 Hz
B84 Hz
C91 Hz
D98 Hz
Mark scheme
71Oct / Nov 2016 · Paper 12 · Q25Show mark scheme →
A51 Hz
B69 Hz
C349 Hz
D469 Hz
Mark scheme
72Oct / Nov 2016 · Paper 13 · Q26Show mark scheme →
A49 Hz
B84 Hz
C91 Hz
D98 Hz
Mark scheme
73May / June 2016 · Paper 12 · Q23Show mark scheme →
A909 Hz
B917 Hz
C1090 Hz
D1100 Hz
Mark scheme
74May / June 2016 · Paper 13 · Q24Show mark scheme →
AThe change in frequency is greater as the car moves away than as it approaches.
BThe greater the speed of the car, the greater the change in observed frequency.
CThe observed frequency is lower as the car moves towards the observer and higher as the car moves away from the observer.
DThe volume of the sound heard by the observer does not change as the car approaches.
Mark scheme
75Feb / March 2016 · Paper 12 · Q20Show mark scheme →
Aall types of wave
Blight and sound waves only
Csound waves and water waves only
Dsound waves only
Mark scheme
76Feb / March 2016 · Paper 12 · Q21Show mark scheme →
A2.04 × 10^13 Hz
B4.37 × 10^14 Hz
C4.57 × 10^14 Hz
D4.79 × 10^14 Hz
Mark scheme