Racing Rings consists of three rods one each of copper, aluminum and PVC, Ring magnet is dropped down the PVC rod, it falls unobstructed, Two metal rods create an induced magnetic field to that adds resistance to the rings travel, metals are different, they fall at different rates
Wave Apparatus Demo - Metal, Consisting of a number of eccentric disc supporting a series of metal rods on revolving the handle. For demonstrating longitudinal and transverse motion.