Explain the difference between a transverse wave and a longitudinal wave. In your answer, describe how the particles move in each type of wave and give one example of each.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
A transverse wave is one in which the particles of the medium vibrate perpendicular to the direction of wave propagation. For example, a wave on a string or a light wave.
A longitudinal wave is one in which the particles vibrate parallel to the direction of wave propagation, producing alternating compressions and rarefactions. For example, a sound wave in air.
Thus the key difference is the direction of particle motion relative to the wave travel, with transverse waves moving perpendicular and longitudinal waves moving parallel.
A longitudinal wave is one in which the particles vibrate parallel to the direction of wave propagation, producing alternating compressions and rarefactions. For example, a sound wave in air.
Thus the key difference is the direction of particle motion relative to the wave travel, with transverse waves moving perpendicular and longitudinal waves moving parallel.
Examiner tips
- Use the phrase "perpendicular to the direction of propagation" for transverse and "parallel to the direction of propagation" for longitudinal.
- Mention compressions and rarefactions for longitudinal waves to secure the extra point.
- Give a clear, correct example for each type of wave.
- Keep the answer concise – 5 marks are enough for a short paragraph.
Common mistakes
- Confusing the direction of particle motion with the direction of energy transfer.
- Giving an incorrect example, such as a sound wave for a transverse wave.
- Omitting the mention of compressions and rarefactions for longitudinal waves.
Mark scheme (5 marks)
- In a transverse wave, particles (or the medium) vibrate/oscillate perpendicular (at right angles) to the direction of wave travel/energy transfer
- In a longitudinal wave, particles vibrate/oscillate parallel to (in the same direction as) the direction of wave travel/energy transfer
- Longitudinal waves have compressions and rarefactions
- Correct example of a transverse wave
- Correct example of a longitudinal wave
Key terms in this question
transverse wave · longitudinal wave
Related
- All Eduqas A-Level Physics revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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