In a transverse wave, the oscillations (vibrations) of the medium are perpendicular (at right angles) to the direction the wave travels.
Features
- The highest points are crests and the lowest points are troughs.
- The wave can be represented as a smooth curve on a displacement-distance graph.
- Transverse waves can be polarised (restricted to vibrate in one plane).
Examples of transverse waves
| Wave | Medium |
|---|---|
| Water waves (surface) | Water surface |
| Light (and all electromagnetic waves) | No medium needed (can travel through a vacuum) |
| S-waves (seismic) | Solid rock |
| Waves on a string or rope | String or rope |
Drawing a transverse wave
Draw a sinusoidal (S-shaped) curve. Label:
- Crest: the point of maximum positive displacement.
- Trough: the point of maximum negative displacement.
- Wavelength: the distance from one crest to the next (or trough to trough).
- Amplitude: the distance from the rest position to a crest.
- Direction of travel: horizontal.
- Direction of vibration: vertical (perpendicular to travel).
Common errors and how to correct them
Saying transverse waves cannot travel through a vacuum. Electromagnetic waves are transverse and travel through a vacuum. It is mechanical transverse waves (like water waves) that need a medium.
Drawing the vibration direction as parallel to travel. Transverse means perpendicular. Always draw the vibration arrow at 90 degrees to the travel arrow.
How to apply this in an exam
State the definition: “vibrations are perpendicular to the direction of energy transfer.” Give an example. If asked to draw, include labelled crests, troughs, wavelength, and amplitude, with arrows showing both vibration and travel directions.
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