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Measurement of the resonance curve (Acoustics)

This semester I´m teaching a physics lab course at the undergrad level and have been trying to involve the use of phyphox where I can for the lab-at-home experiments (we are still teaching virtual). 
I wanted to say special thanks to ´Solid`for the two experiments he shared as they were exactly what I was looking for to design our lab practical on resonating air columns which students could do from their homes. Of course also thanks to the phyphox team as well not just for the app but also constantly updating and making the beta version available with improvements.

Initially I was combining the use of phyphox sound amplitude experiment with a separate web based frequency tone sweep generator, using two phones, but the experiments from Solid were much more convenient, specially the FFT with the accumulated runs, which by the way is also quite useful to use it muted in order to record and accumulate external sounds. In fact, one of my students is using it like that for his end of semester project to record accumulated FFTs of instrument notes (which are convenient to play a couple of times to get good signal to noise ratios).

Here I´m sharing some of the results from a couple of my students from an experiment that could be of interest for others here. Besides doing the simple FFT measurement of a open/closed tube, I had them explore how the frequency spectrum evolved as a function of the effective tube length, which can be achieved simply by adding fixed amounts of water volumes to the tube and taking/saving a new FFT each time (see attached images for effective length vs frequency). After all data has been taken then one can put it all together in 3D image plots. I thought it was a pretty nice way for students to see how each resonant mode evolved with reducing tube lengths. 



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RE: Measurement of the resonance curve (Acoustics) - by esteban.bermudez - 11-05-2021, 10:23 PM

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