Transverse & Longitudinal Waves (Cambridge (CIE) IGCSE Physics): Revision Note

Transverse waves

• Waves can exist as one of two types:

  • Transverse

  • Longitudinal

• Transverse waves are defined as:

Waves where the direction of vibration is at right angles to the direction of propagation

• For a transverse wave, the particles of the medium vibrate perpendicular to the direction in which the wave is travelling

• Mechanical transverse waves can travel through solids and along the surface of a liquid, but not through the body of a liquid or through a gas

• Non-mechanical transverse waves can move in a vacuum

• Examples of waves that can be modelled as transverse are:

  • Electromagnetic waves (such as radio waves, visible light, X-rays)

  • Ripples on the surface of water

  • Seismic S-waves (secondary earthquake waves)

Longitudinal waves

• Longitudinal waves are defined as:

Waves where the direction of vibration is parallel to the direction of propagation

• For a longitudinal wave:

  • The particles of the medium vibrate back and forth parallel to the direction in which the wave travels

  • They can move in solids, liquids and gases

  • They cannot move in a vacuum (since there are no particles)

• The key features of a longitudinal wave are:

  • Regions where the particles of the medium are close together, called compressions

  • Regions where the particles of the medium are spread apart, called rarefactions

• Examples of waves that can be modelled as longitudinal waves are:

  • Sound waves

  • Seismic P-waves (primary earthquake waves)

Difference between transverse and longitudinal waves