How does a Theremin instrument work?
In case the links Del provided are all techno babble to you: Each of the two antennas of the theremin are sensitive to electromagnetic changes. A theremin creates an inductance-capacitance circuit, which in layman’s terms means the device stores electricity until the circuit is disturbed. A hand which has a very slight electric charge will disrupt the field. So the person playing the Theremin is literally functioning as the third prong of an electrical plug, and grounds the current proportionally to the distance from the antenna. That disruption of the electric current is then relayed through circuits that control the pitch and volume.
