Longitudinal wave

Longitudinal waves are <a href="/facts/Wave/fU0HH6St">waves</a> which <a href="/facts/Oscillation/6vSrm84a">oscillate</a> in the direction which is parallel to the direction in which the wave travels and displacement of the medium is in the same (or opposite) direction of the <a href="/facts/Wave_propagation/PXhWIt7k">wave propagation</a>. <a href="/facts/Mechanical_wave/UeWkUcCQ">Mechanical</a> longitudinal waves are also called compressional or compression waves, because they produce <a href="/facts/Compression_(physics)/2wwcVmM0">compression</a> and <a href="/facts/Rarefaction/TCGtjry2">rarefaction</a> when travelling through a medium, and pressure waves, because they produce increases and decreases in <a href="/facts/Pressure/eyc37GRG">pressure</a>. A wave along the length of a stretched <a href="/facts/Slinky/Xc1Brzrd">Slinky</a> toy, where the distance between coils increases and decreases, is a good visualization. Real-world examples include sound waves (vibrations in pressure, a particle of displacement, and particle velocity propagated in an <a href="/facts/Elasticity_(physics)/wcJoIFg1">elastic</a> medium) and seismic <a href="/facts/P_wave/dzv94RBr">P waves</a> (created by earthquakes and explosions).
The other main type of wave is the <a href="/facts/Transverse_wave/WVLe5XKX">transverse wave</a>, in which the displacements of the medium are at right angles to the direction of propagation. Transverse waves, for instance, describe some bulk sound waves in <a href="/facts/Solid/hj5UsXno">solid</a> materials (but not in <a href="/facts/Fluid/tMQ46Tmz">fluids</a>); these are also called "<a href="/facts/Shearing_(physics)/RsTPPauy">shear</a> waves" to differentiate them from the (longitudinal) pressure waves that these materials also support.

Longitudinal wave open-in-new

Longitudinal wave