Waves transfer energy from one place to another. Describe the key features of a wave, including what is meant by amplitude, wavelength, frequency, and wave speed, and explain how frequency and wavelength are related to wave speed.

Eduqas GCSE Physics — 1.5 Features of waves · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Amplitude is the maximum displacement of a point on the wave from its equilibrium position.
Wavelength is the distance between two successive identical points on the wave, e.g. crest to crest or trough to trough.
Frequency is the number of complete waves (cycles) passing a point per second, measured in hertz (Hz).
Wave speed equals frequency multiplied by wavelength (v = f\u00d7\u03bb). Thus, for a given wave speed, a higher frequency gives a shorter wavelength, and vice‑versa.

Examiner tips

  • Use the exact definitions and units (Hz, m, s).
  • Show the relationship v = f\u00d7\u03bb explicitly.
  • Mention the inverse relationship between f and \u03bb for constant v.

Common mistakes

  • Confusing amplitude with wavelength or frequency.
  • Forgetting to include units or the correct equation v = f\u00d7\u03bb.

Mark scheme (4 marks)

  1. Amplitude is the maximum displacement of a point on the wave from its undisturbed (equilibrium/rest) position
  2. Wavelength is the distance between two successive identical points on the wave (e.g. crest to crest or trough to trough)
  3. Frequency is the number of complete waves (cycles) passing a point per second, measured in hertz (Hz)
  4. Wave speed equals frequency multiplied by wavelength — a higher frequency means a shorter wavelength for the same wave speed (or equivalent correct relationship stated)

Key terms in this question

amplitude · wavelength · frequency · wave speed

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