Year 11 · 2025 syllabus · 30 marks · Suggested 45 min
Physics: waves and explanations
A focused assessment of wave quantities, graphs, interference and evidence. The 2025 syllabus starts Year 11 teaching in 2027; this pack matches the site's published 2025 lessons. This is not a whole-course paper.
Check your own evidence
Tick only criteria supported by your response. This is a self-assessment, not a teacher-awarded result or predicted HSC mark. Use the linked lessons to repair missing evidence.
0 of 30 evidence points checked
Question 1 (1 mark)
Which quantity is the number of complete oscillations per second?
Answer and explanation
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
Question 2 (1 mark)
A wave has frequency 5.0 Hz and wavelength 0.80 m. What is its speed?
Answer and explanation
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Question 3 (1 mark)
Which graph lets you read wavelength directly?
Answer and explanation
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Question 4 (1 mark)
Two equal, opposite displacements overlap at a point in a linear medium. What does superposition predict there at that instant?
Answer and explanation
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Question 5 (3 marks)
A source makes 20 complete oscillations in 8.0 s. Calculate frequency and period, showing the relationship between them.
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
Frequency is 2.5 Hz. Period is 0.40 s per cycle. The reciprocal relationship T = 1/f gives the same result.
Question 6 (3 marks)
Distinguish longitudinal and transverse mechanical waves using particle motion, and explain how wave propagation differs from net transport of medium particles.
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
In a transverse wave, particles oscillate perpendicular to propagation; in a longitudinal wave they oscillate parallel to it. In both ideal cases, the disturbance carries energy through particles oscillating about equilibrium positions, rather than carrying each particle along the full path.
Question 7 (3 marks)
A displacement–time record at a fixed point has successive positive peaks at 0.20 s and 0.70 s. A spatial snapshot has adjacent peaks 1.2 m apart. Calculate period, frequency and wave speed.
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
T = 0.50 s, f = 2.0 Hz and λ = 1.2 m. Hence v = fλ = 2.4 m s⁻¹. The time and spatial records provide different wave quantities.
Question 8 (3 marks)
In the data table, does frequency affect wave speed substantially? Calculate each speed and give a cautious conclusion.
| Frequency (Hz) | Wavelength (m) |
|---|---|
| 2 | 3 |
| 3 | 2 |
| 4 | 1.5 |
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
Each trial gives v = 6.0 m s⁻¹. The higher frequencies have shorter wavelengths. These data support constant speed within the tested range and fixed conditions; they do not prove every medium is non-dispersive.
Question 9 (3 marks)
At one point, two waves have simultaneous displacements +3 mm and −1 mm. Find the resultant displacement and explain why a zero resultant elsewhere would not demonstrate zero energy everywhere.
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
The resultant is +2 mm. Adding the signed displacements describes this location at this instant. A zero result at another location is local cancellation, not evidence that the waves or the total energy have disappeared.
Question 10 (3 marks)
A sound source is heard across a room. Explain why a small parcel of air need not travel from the source to the listener, and why sound cannot propagate through an ideal vacuum.
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
Air particles oscillate locally as compressions and rarefactions pass through neighbouring particles. The disturbance carries energy to the listener without the same parcel travelling across the room. Sound is mechanical and cannot travel through an ideal vacuum without a medium.
Question 11 (4 marks)
Design a method to measure wave speed from frequency and wavelength on a wave apparatus. Explain four features that improve the quality of the evidence.
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
Determine source frequency and measure a distance spanning several full wavelengths before dividing by the number. Keep the medium conditions fixed. Repeat measurements and calculate v = fλ for each trial. Report units and discuss uncertainty in identifying peak positions and timing; a long distance measurement reduces relative reading error.
Question 12 (4 marks)
A student uses a displacement–time graph to report ‘wavelength = 0.40 s’. Evaluate and repair the answer, explaining what extra information would be needed to obtain wavelength.
Marking criteria
Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.
One possible response
The value is a period if it spans one full oscillation. It should be T = 0.40 s and f = 2.5 Hz. Wavelength is a distance, so a spatial measurement or the speed is needed. If speed is known, λ = vT.