and oersted was showing there's no relationship between the two. and one of the things he would do is he would line up the piece of wire like this and put it over a magnet, pass a current through it, and you really don't see anything happening. there's no interaction. a student came up after class, gang, and held it in this direction. okay, watch this one, a current is passed over the wire like this, boom. you see that interaction? it turns out there is an interaction between a current-carrying wire and a magnet. and it turns out-- to make a long story short-- the source of all magnetism is moving electric charges. and when the charges move through the wire, they set up about the wire a magnetic field. and that magnetic field is in concentric loops around the wire. if i pass this wire through a hole in a piece of paper and i put a whole lot of little compasses around the wire and no current goes through, all those compasses would point north. but you know what happen if i put a current through that wire? bam, all the compasses will line up with the