How Do Sound Waves Behave in a Closed vs. Open Tube?

[narutodemonki]

Homework Statement

A tuning fork is set up near the end of an air filled tube(open at both ends) of variable length. By changing the length various position of maximum loudness( resonances) can be found. The difference in tube length between adjacent maxima is found to be 10.0 cm
a) wavelength of air of this sound?
b) frequency of tuning fork?
c) would closing the right hand end of tube change 10.0 cm measurement?

Homework Equations

and attempt
for a) I used equation L=n lambda/2, lambda was found to be 0.20m by assuming n=1... not sure why n =1, but i get the right answer. ( did not say 1st harmonic etc.)b) frequency of tuning fork I used v= lambda *f .. and got f=1700 HZ.

c) I am not sure how to answer C) in the answer section it says: no because lambda/2 distance is still between resonance
what I know is closing the right end would made the anti node become a node.

 

[ehild]

You get the first maximum at different length, but the difference in tube length between adjacent maxima stays the same 10.0 cm.

ehild