基本用語 　-Basic terms-

There are two types of waves, longitudinal waves and transverse waves in waves that shake air molecules.

longitudinal wave


The direction of travel and wave vibration are parallel.This is the wave type of sound waves. (Please try to image the P wave of the earthquake / the longitudinal wave)
Looking closely at the longitudinal wave figure, (Blue line part) there are places with high density and low density. For that reason, Another name for the longitudinal wave is "Compressional wave".

‚Transverse wave


The direction of travel and wave vibration are vertical . (Please imagine the S wave / transverse wave of the earthquake)
‚Considering the wave speed as an example of an earthquake, P waves / longitudinal waves are transmitted quickly, S waves / transverse waves are transmitted late.

Plus α

Longitudinal waves and transverse waves have differences in the transmission medium.
Longitudinal wave…　In order to transmit it, you need the power to restore the density to the medium.
Transverse wave…　A force to return lateral deviation to the medium is required.　This force is said to be shear elastic.

For liquids and gases, the force trying to restore the lateral deflection does not work, Transverse waves are transmitted to solid only .
On the other hand, longitudinal waves are not only gas such as airLiquid or solidstill it is transmitted.。However, no sound is transmitted in a vacuum where there is nothing to tell.