Classroom demonstration of Eddy currents
This one is the analog speedometer of my old motorbike (Yamaha Crux) . It works on the principle of electromagnetic induction. There is a metal wire connected with front wheel , it rotates when wheel rotates due to mechanism the cylindrical magnet rotates and so magnetic field lines cut with the aluminium drum over it so Eddy Current loops are generated so due magnetic effect the drum rotates it is also connected with the very soft spiral spring , here the torque due to Eddy currents is balanced by restoring torque produced by the twist. After proper calibration it represents the instantaneous speed of the bike some other gears are also connected so it indicates the total distance travelled also called odometer