Speeds of Waves

There are many different type of wave travelling through many different media. The speed of a wave depends on what type of wave it is and on the media through which it is travelling, in ways that sometimes seem contradictory. For instance, sound waves travel faster in glass than air, but light travels faster in air than glass. This is because of the different nature of each type of wave, with each type of wave being affected in different ways as it passes through each material.

In general the speed of mechanical waves – sound, transverse or compressional – is proportional to the square root of some elastic property of the medium, which measures the 'stiffness' of the bonds or interactions between neighbiouring atoms or molecules in the medium and inversely proportional to the amount of matter in the material, since mass measures the resistance of a material to movement or vibration. In general

Equations and speeds for various types of waves are shown in the table.

In the above table,= density,=Bulk Modulus,=Shear Modulus,=Young's Modulus,=tension,=elextric permittivity of space,=magnetic permeability of space.