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THE TUBE   Foucault pendulum



This short Foucault pendulum has its elliptical distortion compensated by another of Foucault's discoveries, the  magnetic brake
based on eddy currents. A magnet moving over a conducting, non-magnetic metal creates a so-called eddy current which in
turns tends to slow down the magnet. On this pendulum it's the brass ring under the bob which acts as a brake. The rings also
controls the amplitude of the swing, preventing the bob to  bump against the glass tube. 

video

English translation by Jean-Marc Julia