# Some concepts related to the wave motion and its properties

The Wave motion

In the transverse pulse , If the displacements associated with the wave disturbances move in a direction perpendicular to the wave motion , So , The wave is the transverse wave .

In the longitudinal pulse , If the displacements associated with the wave disturbances move in a direction parallel to the wave motion , So , The wave is the longitudinal wave .

The wavelength ( λ ) of the transverse wave is the distance between two successive crests or troughs , The wavelength ( λ ) of the longitudinal wave is the distance between the centers of two successive compressions or rarefactions , and the measuring unit of the wavelength is ” metre ” .

The amplitude of the wave is the maximum displacement achieved by the medium particles away from their rest positions , and its measuring unit is ” metre ” or ” centimetre ” .

The wave velocity is the distance covered by the wave in one second , and the measuring unit of it is metre per second ( m / s ) , The wave velocity represents the velocity of the transfer of the energy carried by the wave .

The wave velocity is constant through the same  medium , but it changes from one medium to another , The velocity of the sound through the gases ( the air ) is smaller than that through the liquids .

The velocity of the sound through the liquids is smaller than that through the solids , The wave frequency is the number of the waves produced from the source in one second , The measuring unit of frequency is ” Hertz ” , and the periodic time of the wave is the time of one wave .

## The law of the wave propagation

It is the relation between the wave velocity ( V ) , its frequency ( F )  and the wavelength ( λ ) in the wave motion .

Wave velocity

The distance covered by the wave in one second ( V ) = the number of the waves produced in one second  ( F ) × wavelength ( λ  ) .