Acoustic Bandgap
Sound waves in a tube are in some ways analogous to electron wavefunctions in a solid. A tube with alternating baffles in it shows a "bandgap": a range of frequencies for which standing waves are not allowed. This is similar to electrons in a semiconductor: there is a "bandgap" of energies that are not allowed. This experiment is an interesting investigation into this acoustic bandgap.
Equipment built by Eric Ayars, used regularly by prior lab students with good results.
Reading
- Ayars handout for this apparatus
- Waves in locally periodic media
- Sonic band structure and localized modes in a density-modulated system: Experiment and Theory
Location
Tubes are above the central cabinet on the west wall of 108, microphone pre-amp boards are in room 108E, cabinet 2.