Start here Magnets have the same types of rules as electric charges If the magnetic poles are the same, they repel . If the magnetic poles are opposite, they attract . A magnet and a piece of iron attract . The most important of these is repulsion . The only way to tell if an object is magnetised is to see if it repels another magnetised object.
Field lines round a magnet Field lines go from North to South.
Magnetic field round a wire When there is no current the compass needles line up with the Earth's magnetic field. A current flowing through a wire produces a circular magnetic field. See what happens when a current flows down the wire. See what happens when the current flows the other way. The magnetic field goes clockwise when viewed from the direction of the current.