A lifeguard at a swimming pool notices that water waves are spreading out from a child splashing in the water. Describe the properties of these water waves, including what is meant by amplitude, frequency, and wavelength, and state the relationship between wave speed, frequency, and wavelength.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
The waves are transverse, so the water particles move perpendicular to the direction of wave propagation.
Amplitude is the maximum displacement of a water particle from its rest position.
Frequency is the number of complete wave cycles that pass a fixed point each second.
Wavelength is the distance between two successive points that are in phase, such as crest to crest or trough to trough.
Wave speed is given by the equation v = f λ, where v is the speed, f the frequency and λ the wavelength.
Amplitude is the maximum displacement of a water particle from its rest position.
Frequency is the number of complete wave cycles that pass a fixed point each second.
Wavelength is the distance between two successive points that are in phase, such as crest to crest or trough to trough.
Wave speed is given by the equation v = f λ, where v is the speed, f the frequency and λ the wavelength.
Examiner tips
- Use the word ‘transverse’ to describe the wave type.
- Define amplitude, frequency and wavelength with the correct wording.
- State the formula v = fλ and explain the symbols.
- Keep the answer concise and to the point.
Common mistakes
- Calling the waves longitudinal instead of transverse.
- Mixing up amplitude with wavelength.
- Forgetting to include the formula v = fλ.
Mark scheme (5 marks)
- Amplitude is the maximum displacement of a point on the wave from its undisturbed/rest/equilibrium position
- Frequency is the number of complete waves (cycles) passing a point per second
- Wavelength is the distance between two successive/adjacent points in phase on the wave (e.g. crest to crest or trough to trough)
- Wave speed = frequency × wavelength (v = fλ)
- The water waves are transverse waves, meaning the displacement of the water is perpendicular/at right angles to the direction of wave travel/energy transfer
Key terms in this question
amplitude · frequency · wavelength · wave speed
Related
- All Eduqas A-Level Physics revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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