A microphone connected to an oscilloscope is used to display two different sound waves, X and Y. Wave X has a greater amplitude than wave Y, but wave Y has a shorter time period than wave X. Describe the differences in what a listener would hear when listening to wave X compared to wave Y.

Pearson Edexcel International GCSE Physics (4PH1) — 3.1 Properties of waves · Describe · 4 marks · View as Markdown

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

A microphone converts the particle oscillations of a sound wave into an electrical signal that is displayed on an oscilloscope. The oscilloscope shows how the voltage of the signal varies with time.

Model answer (4 marks)

Wave X is louder than wave Y
Because wave X has a greater amplitude
Wave Y has a higher pitch than wave X
Because wave Y has a shorter time period, meaning it has a higher frequency

Examiner tips

  • Use the exact phrases from the mark scheme – ‘louder’ and ‘higher pitch’
  • Explain the reason for each effect – amplitude for loudness, period for pitch

Common mistakes

  • Confusing amplitude with frequency or vice‑versa
  • Saying ‘wave Y is louder’ or ‘wave X has a higher pitch’ – the opposite of the mark scheme

Mark scheme (4 marks)

  1. Wave X is louder than wave Y
  2. Because wave X has a greater amplitude (than wave Y)
  3. Wave Y has a higher pitch than wave X
  4. Because wave Y has a shorter time period, meaning it has a higher frequency (than wave X)

Key terms in this question

amplitude · time period

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