Longitudinal waves vs Transverse waves: what's the difference?
GCSE Physics
The two ways a wave can oscillate relative to its direction of travel.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Longitudinal waves vs Transverse waves — side by side
| Longitudinal waves | Transverse waves | |
|---|---|---|
| Oscillation direction | Parallel to energy transfer | Perpendicular to energy transfer |
| Structure | Compressions and rarefactions | Peaks and troughs |
| Examples | Sound, ultrasound, P-waves | Light (all EM waves), water ripples, S-waves |
| Travel through a vacuum? | No (needs a medium) | EM transverse waves can; mechanical ones cannot |
Exam tip — how to tell them apart: Longitudinal = oscillations aLong the direction of travel; transverse = across it.
Common trap: Sound is longitudinal (not transverse) — it needs particles, so it cannot travel through a vacuum.
▶ Practise a "state the difference" question and get it marked (free) →