Question

How can I find the wavelength without knowing the V and having more than 1 resonance. For example for 800f (f: frequency) I had 4 resonances. 1: 6.3 cm 3: 27.3 cm 5: 48.6 cm and 7: 68.6 cm. My teacher gave me one formula 4L/n. But for my table of results they are only asking for one wavelength.

Answer 1

For an open-ended tube, standing waves will be set up inside the tube such that a node is formed at the closed end and an antinode is formed at the open end. For this case, the largest wavelength (fundamental frequency) will be:

the next wavelength will be such that

=>

and so the wavelengths in general will be given by: where n = 1,3,5,7,9,....

Use this to determine the wavelength of the fundamental frequency [n = 1].