Purpose:Demonstrates that magnetic fields are generated around current-carrying wires
Description:A compass needle is mounted directly below a wire on a clear plastic sheet which is positioned on an overhead projector. When a current flows in the wire the compass needle lines up perpendicular to the wire, showing that the current-carrying wire produces a magnetic field perpendicular to the wire. The action is viewed using an overhead projector.
The two geometries are excited individually, as seen in the center (left coil) and right (right coil) photographs. However, notice that the compass near the wire that is not being excited is affected by current in the other coil.