A current-carrying wire produces a magnetic field around it according to the right-hand rule. The strength of the magnetic field decreases with distance from the wire and is directly proportional to the current through the wire. An example calculation is shown for a 0.25 amp current producing a 1x10-7 tesla magnetic field at a distance of 50cm. The magnetic field shape of a circular wire loop is similar to that of a bar magnet. Wires with opposing currents will repel each other.