Open air column is resonating at its second harmonic 580 Hz. If the sound speed is 33om/s, what is the length of this pipe? I got 0.57m as the wavelength, but how do I find the length of the pipe?

Question

anonymous · Answer

For the first harmonic, the wavelength is equal to 2L where L is the length. First harmonic also referred to as fundamental frequency, f0

anonymous · Answer

okay...does that mean I would have to find the first harmonic? I'm not sure :/

anonymous · Answer

Ah sorry read the question wrong I thought it read first harmonic. For the second harmonic the wavelength is equal to the Length of the tube, L. 

Use this equation to calculate wavelengths and tube lengths:

$$\lambda=\frac{ 2L }{ n }$$
where n is the harmonic number. You can see from the equation the second harmonic is just 2L/2 which is just lamda = L.

anonymous · Answer

oh okay, so will it always be 2L/n or can it change?

anonymous · Answer

Sorry, just trying to understand. :/

anonymous · Answer

That equation always applies for when stationary waves are set up. Stationary waves are set up in open air columns like the one in your question.

anonymous · Answer

oh alright. Thank you. :)

anonymous · Answer

Take a look at this website if you want to understand a bit more about where the equation comes from. http://web.utk.edu/~cnattras/Physics221Spring2013/modules/m11/Standing%20sound%20waves.htm You're more than welcome