a stationary wave is created in a column of air in a pipe that is open

Question

A stationary wave is created in a column of air in a pipe that is open at one end.Sound from a small loudspeaker above the open end of the pipe creates the stationary wave.in a nine of length 1.
In practice, the stationary wave extends a short distance e above the end of the pipe.e is known as the end correction and is a constant for any particular pipe. For this first harmonic,lambda/4 occupies a length of l+e where lambda is the wavelength of the sound \text { Show that } \frac{1}{f} \text { is given by: } \frac{1}{f}=\frac{4}{v} l+\frac{4 e}{v} where is the speed of sound in air and fis the frequency of the first harmonic.