Free C.2 Wave model questions for IB Physics (SL & HL), part of C Wave behaviour. Each question has the answer and the marking points an examiner would look for.
Generate a full C.2 Wave Model worksheet →All C Wave behaviour questionsThe intensity of a wave is I at a distance r from a point source. The wave also passes through an absorbing screen placed just before the distance 3r, which reduces its amplitude by a factor of 2.
What is the intensity at 3r, in terms of I?
Answer: A
Which statements about electromagnetic waves in a vacuum are correct?
I. They are transverse waves.
II. They require a medium for propagation.
III. They all travel at the same speed.
Answer: B
A wave passes from one medium into another in which it travels more slowly. What happens to its frequency and its wavelength?
| frequency | wavelength | |
|---|---|---|
| A | unchanged | decreases |
| B | decreases | decreases |
| C | decreases | unchanged |
| D | unchanged | increases |
Answer: A
A transverse wave of frequency 4.0 Hz and wavelength 1.5 m travels along a rope. Points P and Q on the rope are 0.50 m apart.
Calculate the speed of the wave.
Calculate the phase difference between P and Q.
The tension in the rope is increased by a factor of four. The wave speed is proportional to the square root of the tension. Calculate the new wavelength if the frequency is unchanged.
Distinguish between a transverse and a longitudinal wave.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 6.0 m s−1 v = fλ = 6.0 m s−1 ✓ | 1 |
| (b) | 2π/3 rad 0.50/1.5 of a wavelength ✓ = 2π/3 rad (120°) ✓ | 2 |
| (c) | 3.0 m speed doubles to 12 m s−1 ✓ λ = 12/4.0 = 3.0 m ✓ | 2 |
| (d) | oscillation direction transverse: oscillations perpendicular to energy transfer ✓ longitudinal: oscillations parallel to energy transfer ✓ | 2 |
A sound wave of frequency 680 Hz travels in air at 340 m s−1 and then enters water, where its speed is 1500 m s−1.
Calculate the wavelength in air.
Calculate the wavelength in water.
Explain why sound waves cannot be polarized.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 0.50 m λ = 340/680 = 0.50 m ✓ | 1 |
| (b) | 2.2 m frequency is unchanged ✓ λ = 1500/680 = 2.2 m ✓ | 2 |
| (c) | longitudinal sound is a longitudinal wave ✓ polarization needs oscillations perpendicular to the direction of travel ✓ | 2 |
A transverse wave travels along a long rope. Its frequency is 4 Hz, its wavelength is 1.2 m and its amplitude is 4 cm.
Distinguish between a transverse wave and a longitudinal wave.
Calculate the speed of the wave.
Two points on the rope are 0.450 m apart. Calculate their phase difference.
Calculate the maximum speed of a point on the rope, and compare it with the wave speed.
The amplitude is doubled at the same frequency. State the effect on the speed of the wave and on the energy it carries.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | direction of oscillation transverse: oscillation perpendicular to the direction of energy transfer ✓ longitudinal: oscillation parallel to the direction of energy transfer ✓ | 2 |
| (b) | 4.80 m s−1 v = fλ = 4.80 m s−1 ✓ | 1 |
| (c) | 2.36 rad φ = 2πΔxλ ✓ 2.36 rad ✓ | 2 |
| (d) | 1.01 m s−1 vmax = ωA = 2π(4)(0.04) = 1.01 m s−1 ✓ this is different from the wave speed: particles oscillate, the wave transfers energy ✓ | 2 |
| (e) | speed same; energy ×4 speed unchanged (depends on the medium) ✓ energy/intensity is proportional to A2, so it is four times greater ✓ | 2 |
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Meet Riyaz →Original IB-style practice questions written for mentorriyaz.in. These are not IB past paper questions, and this site is not affiliated with or endorsed by the International Baccalaureate Organization. Updated 2026-11-04. Paper generator · mentorriyaz.in