When air is blown into the open pipe,
L = [tex] \frac{nλ}{2} [/tex]
where nis any integral number 1,2,3,4 etc. and λ is the wavelength of the oscillation
⇒λ=[tex] \frac{2L} {n} [/tex]
Note here that n=1 is for fundamental, n=2 is first harmonic and so on..
⇒ third harmonic will be n=4
Given L=6m, n=4, solving for λ we get:
λ=[tex] \frac{(2)*(6)}{4} [/tex] =3m
Relationship of frequency(f), velocity of sound (c) and wavelength(λ) is:
c=f.λ Or f= [tex] \frac{c}{λ} [/tex]
⇒f=[tex] \frac{344}{3} [/tex]
≈115 Hz
