That wasn't too many, was it?
I think what your looking for is this:Producing strong magnetic fieldselectrical switchesChat with our AI personalities
Iron is used for electromagnets.
Electromagnets are used in vending machines to deciever real coins from fake ones. Electromagnets will sort counterfeit money from real money, because most counterfeit money is an iron alloy. Iron is magnetic and gets pulled by the electromagnet, while real coins are not effected.
Electromagnet which uses electric current can be turned on and off.
SOME Electromagnet like permanent magnets have two poles(north/south). Likewise the rules for SOME Electromagnets are the same as those of a permanent magnet(same poles repel, different poles attract).
One of the uses of coal is for power.