Examples of longitudinal waves include:. Longitudinal waves show areas of compression and rarefaction :. In the diagram, the compressions move from left to right and energy is transferred from left to right. In longitudinal waves , the vibrations are parallel to the direction of wave travel. Examples of longitudinal waves include:.
One way to remember the movement of particles in longitudinal waves is to use the 'P' sound: longitudinal waves such as seismic P -waves may be thought of as p ressure or p ush waves as the particles move p arallel to the wave. There are two basic types of wave motion for mechanical waves: longitudinal waves and transverse waves. The animations below demonstrate both types of wave and illustrate the difference between the motion of the wave and the motion of the particles in the medium through which the wave is travelling.
In a longitudinal wave the particle displacement is parallel to the direction of wave propagation. The animation at right shows a one-dimensional longitudinal plane wave propagating down a tube.
The particles do not move down the tube with the wave; they simply oscillate back and forth about their individual equilibrium positions. Pick a single particle and watch its motion. The wave is seen as the motion of the compressed region ie, it is a pressure wave , which moves from left to right.
The second animation at right shows the difference between the oscillatory motion of individual particles and the propagation of the wave through the medium.
The animation also identifies the regions of compression and rarefaction. Since air molecules the particles of the medium are moving in a direction that is parallel to the direction that the wave moves, the sound wave is referred to as a longitudinal wave.
The result of such longitudinal vibrations is the creation of compressions and rarefactions within the air. Regardless of the source of the sound wave - whether it is a vibrating string or the vibrating tines of a tuning fork - sound waves traveling through air are longitudinal waves.
And the essential characteristic of a longitudinal wave that distinguishes it from other types of waves is that the particles of the medium move in a direction parallel to the direction of energy transport. Physics Tutorial. My Cart Subscription Selection.
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