This apparatus is easy and inexpensive to construct and provides a clear and compelling demonstration of Faraday's Law of Induction and the Lorentz force. Two magnets are suspended from springs so that they are free to oscillate vertically. These magnets are placed inside two solenoids (coils of wire). The solenoids are connected. Moving one of the magnets induces a current in the solenoid. This current flows to the other solenoid where is generates a force on the other magnet, causing it to move. Connecting the solenoid leads in different ways produces different results. The instructor can ask students to predict the results of each connection.