Why is there mor than one length of air column that will resonate to some of the frequencies?

I was using tuning forks and a long glass tube in a bigger tube filled with water. When I made it vibrate and put is over the tube while I adjust the tube, it has more than one resonation, why??Why is there mor than one length of air column that will resonate to some of the frequencies?
I am not sure on what you are doing, but there are an infinite amount of ';lengths'; that will make a tuned structure vibrate. This is because of harmonics, while your tuning fork will virate at the fundamental frequency when hit, it will also respond to its 2nd harmonic, 3rd harmonic and so forth, these are the vibrations that vibrate exactly 2 or 3 times as fast of the fundamental vibration.Why is there mor than one length of air column that will resonate to some of the frequencies?
Because all resonance is based on whole multiples of the wavelength.





As long as the length of your column is a whole number multiple of the wavelength, it will resonate. For instance (I'm going to make the numbers big to make it easier) if your wavelength is 1 inch, columns of 1 inch, 2 inches, 3 inches, 4 inches, etc will all resonate, but a column of 2.5 inches will not.





Sound is produced in waves whose wavelength is determined by the pitch of the note. As long as the length of the column is that number times another whole number, you will get a resonance.