Well, curiosity doesn't end there
..I've got a pack of about 20 of those little cute buzzers from a friend. Yesterday, I broke one of them and this is what I explored..
A rounded magnet attached to the outer case just like a small DC motor.
A coil with lots of layers of winding(48SWG I assume) placed in center, that is unmovable. >1mm gap between coil and magnet wall.
A round steel plate sticked to the coil core through magnetism. And the the half-part of the plastic case glued aligning the steelplate outer part.
15ohms DC resistance, and are magnetic. They work well at alarm tones and beep frequencies ie, around 3KHz(Resonant freq.). However as a magnetic sounding device, it produce music(bad) and reacts to dc voltages applied.
**broken link removed**
In this image look at the ring magnet through the hole(bottom view)
However I think piezo buzzers(pulse buzzers that responds to specific frequency only) and those with in-built drivers are also coming in the same dress..many are there in PC add-on cards.