<Li> An electric current inside a wire creates a corresponding circumferential magnetic field outside the wire . Its direction (clockwise or counter-clockwise) depends on the direction of the current in the wire . </Li> <Li> A current is induced in a loop of wire when it is moved toward or away from a magnetic field, or a magnet is moved towards or away from it; the direction of current depends on that of the movement . </Li> <P> While preparing for an evening lecture on 21 April 1820, Hans Christian Ørsted made a surprising observation . As he was setting up his materials, he noticed a compass needle deflected away from magnetic north when the electric current from the battery he was using was switched on and off . This deflection convinced him that magnetic fields radiate from all sides of a wire carrying an electric current, just as light and heat do, and that it confirmed a direct relationship between electricity and magnetism . </P> <P> At the time of discovery, Ørsted did not suggest any satisfactory explanation of the phenomenon, nor did he try to represent the phenomenon in a mathematical framework . However, three months later he began more intensive investigations . Soon thereafter he published his findings, proving that an electric current produces a magnetic field as it flows through a wire . The CGS unit of magnetic induction (oersted) is named in honor of his contributions to the field of electromagnetism . </P>

Who discovered the link between electricity and magnetism