Question

What are the three longest wavelengths for standing sound waves in a 122-cm-long tube under the following conditions.

a)The tube is open at both ends.

b)The tube is open at one end, closed at the other?

Answer 1

given that

length of tube = L = 122cm = 1.22m

when the tube is open at both ends

first harmonic wave length = λ₁= 2L = 2*1.22 = 2.44m

second = λ₂= L = 1.22m

third = λ₃= 2/3*L = 2/3 * 1.22 =0.81m

     2.44m,1.22m,0.81m

when the tube is open at one end

first harmonic = λ₁= 4L = 4 * 1.22=4.88m

third harmonic = λ₃= 4L/3= 4.88/3 =1.62m

fifth harmonic = λ₅= 4L/5 = 0.976m

    4.88m,1.62m,0.976m