Question

A cello and an organ are playing together. The organ plays a pitch of C with a frequency of 65.4 Hz in a pipe open at both ends. The cello plays its C string (a string fixed at both ends), and a beat frequency of 2.5 Hz is heard. The cellist loosens the string until no beat frequency is heard. what is the length of the pipe

Answer 1

λ/2 = length of pipe

The pipe is open at both ends having wavelength of A-N-A or antinode-node-antinode which is 1/2 wavelength

λ = 331 m/s / (65.4 / s) = 5.06 m wavelength of sound

L = 5.06 m / 2 = 2.53 m length of pipe