Freefall

Turn the disk through 180° and watch the neodymium magnets fall at different speeds. Why? And why does the magnet on the wooden rod fall freely?

The magnet on the wooden rod falls freely, while the magnets around the metal rods are subject to braking forces. When a magnet moves across an electrical conductor, an induced current starts to flow and gives rise to a magnetic field. This magnetic field brakes the fall. None of the four metal rods is magnetic, but three of them are conductors. The higher the electrical conductivity of a material, the stronger is the current and thus the magnetic field. This phenomenon is used, for example, to measure energy and to damp mechanical oscillations.