Ressonância acústica
Blow across a bottle and it sings at one particular note. This simulation shows the standing wave forming inside an air column and lets you change its length to hear and see the resonant frequency shift.
Como usar esta simulação
- Change the length of the air column
- Switch between open and closed ends
- Sweep the driving frequency to find each resonance
O que observar
- Resonance occurs only at specific frequencies, not continuously
- A closed pipe produces only odd harmonics
- Halving the length doubles every resonant frequency
A física por trás
An air column resonates when a whole number of half or quarter wavelengths fits its length. A pipe open at both ends has antinodes at each end and resonates at f = nv/2L; a pipe closed at one end has a node there and resonates at f = nv/4L with odd n only. That difference is why a closed pipe sounds an octave lower than an open pipe of the same length.