Radio

Jiggle a collection of electrons up and down one million times a second and a 1-MegaHertz radio signal will be created. Change the vibration frequency and the frequency of the radio signal will change.

Radio transmitters are alternating voltage generators. The constantly changing voltage from the transmitter creates a changing electric field within the antenna. This alternating field pushes and pulls on the conduction electrons in the wire that are free to move. The resulting charge acceleration produces the radio signal that moves away from the antenna. The radio signal causes smaller sympathetic radio frequency currents in any distant electrical conductor that can act as a receiving antenna.