How can a radio signal be used to turn something on?
In other words, how would I use a radio signal to complete a circuit on the receiving end? (i guess you'd call it a remote control). I think I understand the bit about the receiver resonating with the transmitted signal (and the creation and transmission of that signal), but I don't get what happens after that to make the signal usable in a mechanical way, as opposed to audio.
any links or direct explanations are most appreciated. :)