# Homework Help: Graphing Wavelength vs Inverse freq. or Period

1. Oct 23, 2008

### PSEYE

According to our lab manual, the graph of Wavelength vs Period : the slope should be the speed of sound. Well, I have a negative slope of -32.2 which is ridiculous, but I can't find out what I'm doing wrong. We had 5 tuning forks , say for instance, 512Hz...the inverse
1/f = 1/512= 0.00195 , im graphing this on the x-axis and Wavelength on the Y axis. This experiment was done with 2 tubes, one fitted into another, and you're supposed to pull the smaller tube out until the particular tuning for resonates. You are to take the distance of the pipe + the extended portion of the other pipe at 3 different places you hear resonance...then you are supposed to take the difference of the average and double it - that should be your wavelength...example

the tube is 90cm long
first trial @ 512 Hz - heard first resonance at 98.5cm or 8.5 depending...our lab instructor told us to use the entire distance so i did. Heard second resonance at 124cm, and 3rd resonance at 165. I took the difference between these three values and averaged it, then doubled it - i got 66.50cm or 0.665m I did this with 4 other tuning forks , got my info and graphed a negative slope that wasn't even close to being a straight line.

Can anyone give me a clue as to what I'm doing wrong?

Thanks.

oh btw, this is for lab : Resonance in Air Columns.

2. Oct 23, 2008

### Redbelly98

Staff Emeritus
If your textbook gives the actual speed of sound in air, you can use that to check whether the wavelength you get is close to what you expect for each frequency.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook