Question

Find the fundamental, first overtone and second overtone frequencies of an open organ pipe of length 20 cm. The speed of sound in air is 340 m/s. 

Answer 1

The resonant frequencies in an open organ pipe is given as, 

νₙ = nV/2L, where V = 340 m/s, L = 20 cm =0.20 m 

→νₙ = n*(340/2*0.20) =n*3400/4 =n*850 Hz. For the fundamental frequency, n = 1, ν₀ = 1*850 Hz =850 Hz  

For the first overtone frequency, n = 2, 

ν₁ = 2*850 Hz = 1700 Hz  

For the second overtone frequency, n = 3, 

ν₂ = 3*850 Hz =2550 Hz