Longitudinal & Transverse Waves (AQA A Level Physics) : Revision Note

Defining Transverse & Longitudinal Waves

• In mechanical waves, particles oscillate about fixed points

• There are two types of waves:

  • Transverse waves

  • Longitudinal waves

• Each type of wave can be distinguished by its direction of vibration relative to its direction of travel

Transverse Waves

• A transverse wave is defined as:

A wave in which the particles oscillate perpendicular to the direction of the wave travel (and energy transfer)

• Transverse waves show areas of crests (peaks) and troughs

Diagram of a transverse wave

• Examples of transverse waves are:

  • Electromagnetic waves e.g. radio, visible light, UV

  • Vibrations on a guitar string

• Transverse waves can be shown on a rope

• Transverse waves can be polarised

Longitudinal Waves

• A longitudinal wave is defined as:

A wave in which the particles oscillate parallel to the direction of the wave travel (and energy transfer)

• Longitudinal waves show areas of compressions and rarefactions

  • Compressions are regions of increased pressure

  • Rarefactions are regions of decreased pressure

Diagram of a longitudinal wave

• Examples of longitudinal waves are:

  • Sound waves

  • Ultrasound waves

• Longitudinal waves can be shown on a slinky spring

• Longitudinal waves cannot be polarised

• Energy is transmitted through the wave

  • The particles in the medium vibrate as they are given energy

  • The compressions cause the nearby particles to also vibrate with more energy

  • This produces a compression further along in the medium

A wavelength on a longitudinal wave is the distance between two compressions or two rarefactions

Examples of Transverse Waves & Longitudinal Waves

• Energy is transferred through moving oscillations or vibrations

• This can be demonstrated visually using ropes or springs

Waves can be shown through vibrations in ropes or springs

• The oscillations, or vibrations, can be perpendicular or parallel to the direction of wave travel:

  • Waves which oscillate in a perpendicular direction are transverse waves

  • Waves which oscillate in a parallel direction are longitudinal waves

• Examples of transverse waves are:

  • Electromagnetic waves e.g. radio, visible light, UV

  • Vibrations on a guitar string

  • Waves on a string

  • Seismic (S) waves

• Examples of longitudinal waves are:

  • Sound waves

  • Ultrasound waves

  • Waves through a slinky coil

  • Seismic (P) waves