# Homework Help: Resonance in Closed air columns

1. Mar 11, 2009

### Fibonacci

is is based on the experiment where we had to find the point in which tuning fork forces air inside open-ended air column into resonance, the length of the tube is altered by changing the water level in the tube.

the water level can be altered by raising or lowering a reservoir of water, thus decreasing or increasing length of the vibrational system. the first harmonic is produced when the length of the tube is smaller than the length of the tube in the third harmonic. this idea is correct, right??

ok well if this is corrrect, do you agree that the thrid harmonic will have triple the frequency of the first harmonic??

if my above assumptions are correct, then how come in my text book it said that: increase length of the vibrational system increases the wavelength and decreases tje natural frequency of that system, conversely, a decrease in length of the vibrational system will increase the natural frequency as wavelength is decreased.
i understand this explanation from the book, but somehow it seens to condradict what i said about if the length of the vibrational system is increased, third harmonic (higher frequency)
is heard and if i decrease it the first harmonic (lower frequency) is heard.

could someone spot my mistakes or why this is so??
hoped that make sense