Transverse and longitudinal waves
Longitudinal waves
In A wave that moves in the same direction as the direction in which the particles are vibrating., 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 An area of increased pressure. In longitudinal waves, the particles in areas of compression are closer together than on average. and An area of reduced pressure. In longitudinal waves, the particles in areas of rarefaction are further apart than on average.:
- 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.
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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 A material through which a wave can be transmitted (propagate)..
Sound waves
Sound waves are A wave that moves in the same direction as the direction in which the particles are vibrating.. They cause particles to vibrate parallel to the direction of wave travel. The Repeated movements back and forth (about a fixed point). can travel through solids, liquids or gases. The speed of sound depends on the A material through which a wave can be transmitted (propagate). through which it is travelling. When travelling through air, the speed of sound is about 330 metres per second (m/s). Sound cannot travel through a A volume that contains no matter. because there are no particles to carry the vibrations.
Transverse waves
In A wave that moves in a direction at right angles to the way in which the particles are vibrating., 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.
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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.