This apparatus is ideal for demonstrating Faraday's law of electromagnetic induction. It consists of a clear plastic tube containing a powerful magnet, with a 400 turn coil bonded onto the surface of the tube. When the tube is inverted the magnet passes through the coil inducing a voltage on the coil terminals. Students can use an oscilloscope or datalogger to easily see the induced voltage. This is an ideal precursor to understanding generator theory.