C.2 Wave model questions for IB Physics

113 questions on Wave model, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.

IB Physics
Part of C Wave behaviour
SL and HL

Questions by paper and level

SL and HL questions are for students at either level. HL only questions cover what only HL students study.

Paper	SL and HL	HL only	All
Paper 1A	36	1	37
Paper 1B	8	0	8
Paper 2	54	14	68
Every paper	98	15	113

Counted on 10 November 2026

Questions to try

Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.

Question 1 · PHY-00527Paper 1A · 1 mark

A student moves one end of a long horizontal rope up and down, so that a transverse wave travels along the rope. A small ribbon is tied to the rope halfway along its length.

Which describes the motion of the ribbon while the wave passes?

A
It moves along the rope at the speed of the wave.
B
It oscillates vertically about a fixed position.
C
It oscillates horizontally, along the rope, about a fixed position.
D
It oscillates vertically and drifts slowly along the rope in the direction of the wave.

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Question 2 · PHY-00980Paper 1B · 12 marks

A group of students use the arrangement shown to measure the speed of sound in air. A loudspeaker connected to a signal generator emits sound of frequency $f$ . Microphone A is fixed close to the loudspeaker. Microphone B can be moved along a metre rule, directly away from the loudspeaker. Both microphones are connected to a dual-trace oscilloscope.

A signal generator connected to a loudspeaker on a bench. Microphone A is fixed just in front of the loudspeaker. Microphone B sits further along a metre rule and can be moved away from the loudspeaker, shown by a double arrow. Both microphones are wired to an oscilloscope above.

For each frequency, the students move B until its trace is in phase with the trace from A and record the position of B. They then move B further away until the two traces have come back into phase four more times, and record the distance $D$ moved by B. $D$ is equal to four wavelengths. The uncertainty in $D$ is ±1.0 cm. The air temperature is 21 °C.

$f$ / Hz	$D$ / cm ± 1.0 cm	$λ$ / cm	$\frac{1}{f}$ / $10^{- 4}$ s
1500	92.1	23.0	6.67
2000	68.4	17.1	5.00
2500	55.3	13.8	4.00
3000	45.6	11.4	3.33
3500	39.5	9.9	2.86
4000	34.1	8.5	2.50

(a)
State the absolute uncertainty in $λ$ .
1 mark
(b)
Explain why the students measured the distance moved by B for four wavelengths rather than for one.
2 marks
(c)
Calculate the largest percentage uncertainty in $λ$ in these data.
2 marks
(d)
Outline why the students plot $λ$ against $\frac{1}{f}$ .
1 mark
(e)
The graph shows the variation of $λ$ with $\frac{1}{f}$ , with the line of best fit.
Determine, using the graph, the speed of sound in air.
3 marks
(f)
The students draw the lines of maximum and minimum gradient that pass through all the error bars. These lines give speeds of 356 m s^-1 and 336 m s^-1. The accepted speed of sound in air at 21 °C is 344 m s^-1.
Comment on whether the students' result is consistent with the accepted value.
2 marks
(g)
The students propose extending the investigation to a frequency of 400 Hz. Suggest one practical difficulty they would meet.
1 mark

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Question 3 · PHY-00226Paper 2 · HL only · 20 marks

A rover on the surface of Mars launches a small sample capsule of mass 0.50 kg from a level plain. The capsule leaves the launcher at ground level with a speed of $42 {m s}^{- 1}$ at $50^{\circ}$ above the horizontal.

The following data are given:

mass of Mars $= 6.42 \times 10^{23} kg$
radius of Mars $= 3.39 \times 10^{6} m$

The atmosphere of Mars is very thin. Ignore air resistance unless a part says otherwise.

(a)
Show that the gravitational field strength at the surface of Mars is about $3.7 {N kg}^{- 1}$ .
2 marks
(b)(i)
Calculate the time of flight of the capsule.
2 marks
(b)(ii)
Calculate the horizontal distance travelled by the capsule.
2 marks
(b)(iii)
Calculate the maximum height reached by the capsule.
2 marks
(c)
The same launcher is used on Earth, with the same launch speed and angle. Determine the ratio $\frac{horizontal distance on Mars}{horizontal distance on Earth}$ . Ignore air resistance on Earth.
2 marks
(d)
Explain, without calculation, why the capsule lands with the same speed as it was launched.
2 marks
(e)(i)
A later mission must send a sample capsule away from Mars completely. Show that the escape speed from the surface of Mars is about $5 {km s}^{- 1}$ .
2 marks
(e)(ii)
Calculate the minimum energy needed to move the 0.50 kg capsule from the surface of Mars to infinity.
2 marks
(e)(iii)
Outline why the escape speed does not depend on the direction in which the capsule is launched.
1 mark
(f)
Radio signals from the rover travel to Earth at the speed of light. On one day the distance between Mars and Earth is $2.25 \times 10^{11} m$ . Calculate the time taken for a signal from the rover to reach Earth.
1 mark
(g)
The thin atmosphere of Mars does exert a small drag force on the capsule. Predict how the horizontal distance and the speed on landing compare with your answers to (b)(ii) and (d).
2 marks

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Question 4 · PHY-00528Paper 1A · 1 mark

Three waves are:

sound from a dolphin travelling through seawater
infrared radiation emitted by a heater
a pulse on a slinky spring whose end is pushed and pulled along the length of the spring

Which row correctly classifies the waves?

	Sound in seawater	Infrared radiation	Pulse on the slinky
A.	longitudinal	transverse	longitudinal
B.	longitudinal	longitudinal	transverse
C.	transverse	transverse	longitudinal
D.	transverse	longitudinal	transverse

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Question 5 · PHY-00981Paper 1B · 12 marks

A student investigates how the speed $v$ of a pulse on the surface of water depends on the depth $h$ of the water. She uses a rectangular tray 0.800 m long. She lifts one end of the tray slightly and lowers it quickly, which sends a single pulse along the tray. The pulse reflects at the far end and returns.

Side view of a long rectangular tray, 0.800 m long, containing water of depth h. A single hump-shaped pulse on the water surface near the left end has an arrow showing it moving to the right.

For each depth, she uses a stopwatch to measure, three times, the time $t$ for the pulse to travel to the far end and back. The depth is measured with a ruler with an uncertainty of ±0.1 cm.

$h$ / cm ± 0.1 cm	$t_{1}$ / s	$t_{2}$ / s	$t_{3}$ / s	mean $t$ / s	$v^{2}$ / m² s^-2
1.0	5.21	5.08	5.17	5.15	0.097
2.0	3.73	3.62	3.68	3.68	0.189
3.0	2.91	3.02	2.96
4.0	2.60	2.53	2.58	2.57	0.388
5.0	2.28	2.34	2.29	2.30	0.484
6.0	2.12	2.05	2.10	2.09	0.586

(a)
Calculate the percentage uncertainty in $h$ for the smallest depth.
1 mark
(b)
Determine, for $h$ = 3.0 cm, the mean time $t$ and its absolute uncertainty.
2 marks
(c)
Show that $v^{2}$ for $h$ = 3.0 cm is about 0.29 m² s^-2.
1 mark
(d)
Theory suggests that $v = \sqrt{g h}$ for a pulse in shallow water. Explain why the student plots $v^{2}$ against $h$ .
2 marks
(e)
The graph shows the variation of $v^{2}$ with $h$ , with error bars and the line of best fit.
Determine $g$ using the graph.
3 marks
(f)
Discuss whether the data support the theory.
2 marks
(g)
Suggest why the student timed the pulse to the far end and back rather than over one length of the tray.
1 mark

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Question 6 · PHY-00351Paper 2 · HL only · 8 marks

An aircraft flies horizontally at a constant $200 {m s}^{- 1}$ relative to the ground. The air is still. The speed of sound in the air is $340 {m s}^{- 1}$ relative to the air.

(a)
State what is meant by a reference frame.
1 mark
(b)
Calculate, using the Galilean transformation, the speed relative to the aircraft of sound from its engines that travels straight ahead of the aircraft and of sound that travels straight behind it.
2 marks
(c)
State the speed of the sound travelling straight ahead relative to an observer standing on the ground.
1 mark
(d)
The aircraft switches on a landing light that shines straight ahead. State the speed of this light relative to the aircraft predicted by the Galilean transformation if the light travels at $c$ relative to the ground.
1 mark
(e)
State the speed of the light relative to the aircraft according to special relativity.
1 mark
(f)
Light, unlike sound, needs no medium. Outline how the postulates of special relativity changed the way the speed of light is understood compared with Galilean relativity.
2 marks

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