Electromagnetic Waves

From PascaI's principie which was stated in 1652 by Biaise PascaI, according to which a change in pressure applied to an enclosed incompressible fluid is transmitted undiminshed to every portion of the fluid and uo the walls of its container. This pressure change is independent of height. Hence, on biowing air through a closed pipe containing Iiquid, pressure will increase in all directions.

Speed of wave on a string

or

or
or ...(i)
Given, and


Substituting the values in E (i), we get


Percent increase in tension

When an observer moves towards an stationary source of sound, then apparent frequency heard by the observer increases. The apparent frequency heard in this situation

As source is stationary hence,

Given,
Substituting in the relation for , we have

Motion of observer does not affect the wavelength reaching the observer, hence, wavelength remains .
Note : When the speed of source and observer are much lesser than that of sound, the change in frequency becomes independent of the fact whether the source is moving or the observer.