What is the Meaning of End Correction?

[bepunctual]

I wonder if someone could explain what is meant by 'End Correction'

Any help is appriciated! thanks

 

[Doc Al]

In what context is the term being used?

 

[bepunctual]

We did an experiment to measure the velocity of sound by air colum by holding a vibrating tuning fork above a plastuc tube with one end in water. by moving the tube up and down we then found the shortest length of the air column that produced the loudest sound.

by plotting length against 1/f and finding the gradient of the line, we could find the velocity of sound. however the graph did not go through 0,0 and our teacher suggested this was due to 'end correction' but that we had to research what this meant.

I have looked in several books, and searched on the internet, but am unable to come up with an understandable meaning for me.

hope this helps!

 

[Doc Al]

That's what I thought you were talking about. In elementary treatments of standing sound waves in pipes, the antinode is treated as being exactly at the end of the pipe. But it's more complicated than that due to the interaction of the sound with the open air. It turns out that the "effective length" of a pipe depends on the geometry of the pipe end and how the air in the pipe interacts with the air outside the pipe. These are the "end corrections".

I had a bit of trouble myself trying to find something on the web to help you, but here's a start:
http://www.phys.unsw.edu.au/~jw/musFAQ.html#end
http://www.du.edu/~jcalvert/waves/pipes.htm