Longitudinal Waves
Longitudinal Waves
- A longitudinal wave is one where the particles oscillate parallel to the;
- Propagation of the wave
- Direction of energy transfer
- Longitudinal waves show areas of
- High pressure, called compressions
- Low pressure, called rarefactions
Diagram of a longitudinal wave
- Examples of longitudinal waves are:
- Sound waves
- Ultrasound waves
- P-waves caused by earthquakes
- Longitudinal waves cannot be polarised
Labelling Longitudinal Waves
- You learned how to describe the properties of a wave, such as amplitude and wavelength at the start of this topic
- The diagram shows a wavelength on a longitudinal wave
Wavelength is shown on a longitudinal wave
Examiner Tip
Questions about longitudinal waves typically start by asking for a definition, so be ready with a statement about areas of high and low pressure and the keywords compression and rarefaction.
Be careful with graphs of waves and don't assume a sinusoidal-shaped graph represents a transverse wave. Longitudinal waves can also look sinusoidal when plotted on a graph - make sure you read the question and look for whether the wave travels parallel (longitudinal) or perpendicular (transverse) to the direction of travel to confirm which type of wave it is.
