Transverse & Longitudinal Waves (SQA National 5 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 energy transfer

• For a transverse wave, the oscillation (vibration) is perpendicular to (at right angles to) the direction the wave is travelling

• Mechanical transverse waves can move in solids, and on the surface of liquids, but not in liquids or gases

• Non-mechanical transverse waves can move in a vacuum

Transverse wave motion

Transverse waves can be seen in a rope when it is moved quickly up and down

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

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

  • 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 energy transfer is in the same direction as the wave motion

  • They can move in solids, liquids and gases

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

• The key features of a longitudinal wave are where the points are:

  • Close together, called compressions

  • Spaced apart, called rarefactions

  Longitudinal wave motion

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

  • Sound waves

  • Seismic P-waves (primary earthquake waves)

Differences between transverse and longitudinal waves

Comparing transverse and longitudinal waves