A magnet and a similarly sized piece of non-magnetic metal are allowed to fall through an aluminium tube, one after the other. The non-magnetic piece falls through the tube easily, while the magnet takes several seconds to fall the same distance.
How does it work?
The magnet generates so-called eddy currents which act as brakes due to the magnetic field induced.
The same principle applies for example in electric cars, where braking converts the kinetic energy of the wheels back into electrical energy to be stored in the battery
