A student is studying waves on the surface of water in a ripple tank. The student observes that the waves have a small amplitude and a high frequency. Explain what is meant by the terms amplitude and frequency, and describe how each of these features would appear to an observer watching the water surface.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Waves on the surface of water in a ripple tank can be used to study wave behaviour. The student notes that the waves appear to have a small amplitude and a high frequency.
Model answer (4 marks)
Amplitude is the maximum displacement of a point on the wave from its rest (equilibrium) position. A small amplitude means the observer would see waves with low or small peaks and shallow or small troughs – the water surface barely rises or falls. Frequency is the number of complete waves (cycles) passing a given point per second. A high frequency means the observer would see waves passing very rapidly – the crests would arrive very close together in time and the waves would appear closely spaced.
Examiner tips
- Use the exact definitions of amplitude and frequency.
- Show how a small amplitude looks – low peaks, shallow troughs. Show how a high frequency looks – many crests per second, close spacing.
- Keep the answer concise – 4 marks only.
- Use UK spelling (e.g. ‘crests’).
Common mistakes
- Confusing amplitude with wavelength or period. Describing frequency as speed rather than cycles per second. Using vague terms like ‘small’ or ‘fast’ without explanation.
Mark scheme (4 marks)
- Amplitude is the maximum displacement of a point on the wave from its rest (equilibrium) position
- A small amplitude means the observer would see waves with low/small peaks and shallow/small troughs — the water surface barely rises or falls
- Frequency is the number of complete waves (cycles) passing a given point per second
- A high frequency means the observer would see waves passing very rapidly / the crests would arrive very close together in time / the waves would appear closely spaced
Key terms in this question
Related
- All WJEC GCSE Physics (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Features of waves questions
- A sound wave travels through air. The wave has a period of 0.002 s and a speed o…
- A musician plucks a guitar string. The string vibrates and produces a sound wave…
- A student says: 'A wave with a higher frequency must have a longer wavelength.' …
- Describe the features of a wave, including what is meant by amplitude, wavelengt…