# Transverse and longitudinal waves

In a transverse wave the medium moves at right angles to the wave direction. In a longitudinal wave it moves along the direction.

Physics (university) · Part 05: Oscillations and waves · Card 7 of 11 · Last updated 2026-10-19

## Analogy

A shaken rope is transverse. A pushed and pulled spring is longitudinal.

## Example

**Which is which**

Rope wave: transverse
Sound wave: longitudinal
Light: transverse

## In practice

Light and waves on a string are transverse. Sound in air is longitudinal.

## Practice

### Flashcards

- **Which waves need a medium: light or sound?** Sound. Light can travel through empty space.

## Questions people ask

### Why can light travel through space but sound cannot?

Light is an electromagnetic wave. Its fields carry the wave, so it needs no material. Sound is a vibration of particles that bump into each other, so it needs air, water or a solid. Space is almost empty, so sound has nothing to travel through.

### What is a compression?

A compression is a region in a longitudinal wave where particles are pushed close together, so the pressure is higher. The next region, where they are spread apart, is called a rarefaction. The distance between two compressions is one wavelength.

## Related concepts

- [Simple harmonic motion](https://studyvisually.com/learn/science/physics-university/physics-university-part-5/physics-university-part-5-concept-1)
- [Period and frequency](https://studyvisually.com/learn/science/physics-university/physics-university-part-5/physics-university-part-5-concept-2)
- [Mass on a spring](https://studyvisually.com/learn/science/physics-university/physics-university-part-5/physics-university-part-5-concept-3)
- [Simple pendulum](https://studyvisually.com/learn/science/physics-university/physics-university-part-5/physics-university-part-5-concept-4)

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