A sound wave travelling through air has a frequency of 440 Hz and a wavelength of 0.75 m. Explain what is meant by the terms frequency, wavelength, and amplitude of a wave, and state how increasing the amplitude of the sound wave would affect the energy it carries.

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

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

Model answer (4 marks)

Frequency is the number of complete waves passing a point each second.
Wavelength is the distance between two successive identical points on the wave, for example crest to crest or trough to trough.
Amplitude is the maximum displacement of a point on the wave from its equilibrium position.
Increasing the amplitude increases the energy carried by the sound wave.

Examiner tips

  • Use the exact definitions from the mark scheme. Show the relationship between amplitude and energy. Keep the answer concise and to the point.

Common mistakes

  • Confusing wavelength with frequency. Using vague terms like ‘size’ for amplitude. Forgetting to state that higher amplitude means more energy.

Mark scheme (4 marks)

  1. Frequency is the number of complete waves (cycles/oscillations) passing a point per second
  2. Wavelength is the distance between two successive identical points on the wave (e.g. crest to crest or trough to trough)
  3. Amplitude is the maximum displacement of a point on the wave from its undisturbed (equilibrium/rest) position
  4. Increasing the amplitude increases the energy carried by the wave

Key terms in this question

frequency · wavelength · amplitude

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