# Harmonics and the frequencies

Let's say we had a pipe which was closed on one side and open on the other. We can find the wavelength for the first harmonic. To find the second harmonic we just add one more antinode and find a new frequency and wavelength. What confuses me is that both the frequency and wavelength are changing but, this contrasts the experiment done to calculate speed of sound with resonance.

In that experiment, is there a single tuning fork used or are 2 tuning forks? This is because we actually increase the size of the pipe/tube so that the difference is $\lambda/2$. Now if we sub all of that data into $v = f(\lambda)$, which frequency are we using?

• Not clear what experiment you refer to that measures speed of sound with a tuning fork - can you add more details? Commented May 10, 2015 at 19:20

The basic idea for a closed-end tube is that the overtone frequencies follow $$f_n=(2n+1)\frac{v}{4L},$$ where n=0 for the fundamental and n=1, 2, 3, etc for the overtones.