Describe how a longitudinal wave differs from a transverse wave. In your answer, refer to the direction of oscillation, and give one example of each type of wave.

AQA A-Level Physics (7408) — 3.3.1 Progressive and Stationary Waves · Describe · 5 marks · View as Markdown

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

Waves transfer energy from one place to another. There are two main types of wave: transverse and longitudinal.

Model answer (5 marks)

In a transverse wave the particles of the medium oscillate perpendicular to the direction of wave travel. For example, light waves are transverse.
In a longitudinal wave the particles oscillate parallel to the direction of wave travel, producing alternating compressions and rarefactions. For example, sound waves are longitudinal.

Examiner tips

Use the terms ‘perpendicular’ and ‘parallel’ to show understanding of oscillation direction.
Mention compressions/rarefactions for longitudinal waves.
Give a clear example for each type (light and sound).
Keep the answer concise to fit the 5‑mark limit.

Common mistakes

Confusing the direction of oscillation with the direction of wave travel.
Giving an incorrect example such as a water wave for a longitudinal wave.
Omitting the key feature of compressions and rarefactions in longitudinal waves.

Mark scheme (5 marks)

In a transverse wave, oscillations are perpendicular (at right angles) to the direction of travel/energy transfer.
In a longitudinal wave, oscillations are parallel to the direction of travel/energy transfer.
Longitudinal waves have compressions and rarefactions.
Correct example of a transverse wave (e.g. any electromagnetic wave / light / water waves).
Correct example of a longitudinal wave (e.g. sound waves).

Key terms in this question

transverse wave · longitudinal wave · oscillation