And some elements that have positive feedbacks: Led, lamp, capacitor (and on the same topic of electricity - solar panels, but they did not receive feedbacks)
I like LED, lamp is nearenough LED with the diode feature and i like capacitor. So: LED - Gives off photons, current can only go one way Capacitor - PSCN charges it and it will hold all charge given to it. NSCN will uncharge it and all current will be released. Amount of charge varies with size of capacitor
lolzy, may be... But may be useful too. Like people wrote wood can be converted into coal, coal can burn very slowly and it can make distilled water from water/salt water. Not bad functionality i think