What are some real-life applications of the singing wine glass experiment?
People have actually used singing wine glasses to make music. An example is in my first youtube reference link below. Also, I know that on the TV show MacGyver, he was able to break through a lock that used the wine glasses. Each lock key operated on receiving a specific 'frequency,' or musical note. In the proper order, the lock would pop open. From what I am seeing, it shows up at about minute 34 in the other video below.
The whole idea of this is sound resonance and frequency, which also runs through materials as well as air. For instance, one way people find fractures in iron girders is by running a sound "through" it at one end. If they get the same sound out the other end, they know the girder is "good"; it followed resonance. If the sound is different, the girder is bad. I know of one person in college who did this for a thesis, or dissertation, but on human bones. If the sound was the same, there was no fracture in the bone. If the sound was different, there was a fracture in the bone, however hairline it may have been.