In 1820, Hans Christian Oersted was giving a public demonstration to show that electricity, heat, and light were related. He connected a source of electricity to a platinum wire and demonstrated that the wire became hot and began to glow. He happened to have a compass on hand for another experiment he was planning and decided to see if the electricity had any effect on the compass needle. He observed that when the current was running through the wire, it made the compass needle turn so it was perpendicular to the wire. A drawing of this is seen below. Apparently, his audience was unimpressed, but Oersted realized that the cause of the compass moving was the result of a magnetic field produced by the electric current in the wire.