If you blow across the open end of a soda bottle and produce a tone of 250 Hz, what will be the frequency of the next harmonic heard if you blow much harder?

Answer 1

Since this is a closed pipe, only odd harmonics are possible. Therefore, if the tone of 250 Hz is the lowest (first) harmonic, the next harmonic will be the third harmonic, 3 x 250 Hz = 750 Hz.