大象传媒

Transverse and longitudinal waves

Longitudinal waves

In , the vibrations are parallel to the direction of wave travel.

Examples of longitudinal waves include:

  • sound waves
  • ultrasound waves
  • seismic P-waves

Longitudinal waves show areas of and :

  • compressions are regions of high pressure due to particles being close together
  • rarefactions are regions of low pressure due to particles being spread further apart

Longitudinal waves are often demonstrated by pushing and pulling a stretched slinky spring.

Image gallerySkip image gallerySlide 1 of 3, An outstretched slinky spring,

In the diagram, the compressions move from left to right and energy is transferred from left to right. However, none of the particles are transported along a longitudinal wave. Instead, they move backwards and forwards between compressions as the wave is transmitted through the .

Transverse waves

In , the vibrations are at right angles to the direction of wave travel.

Examples of transverse waves include:

  • ripples on the surface of water
  • vibrations in a guitar string
  • a Mexican wave in a sports stadium
  • electromagnetic waves, eg light waves, microwaves, radio waves
  • seismic S-waves

Transverse waves are often demonstrated by moving a rope rapidly up and down.

Image gallerySkip image gallerySlide 1 of 3, A hand holds a length of rope taut,

In the diagram the rope moves up and down, producing peaks and troughs. Energy is transferred from left to right. However, none of the particles are transported along a transverse wave. The particles move up and down as the wave is transmitted through the medium.