Dave Johnson built this mesmerizing hand cranked machine for rare earth ball magnets for his father’s 75th birthday. At about the 1:15 mark you’ll witness the remarkable behavior of the ball magnets as they are fed in a continuous loop through the innards of the machine. Johnson explains the machine in detail in the description accompanying the YouTube video.
This machine manipulates small spherical rare earth magnets, slicing one at a time from the end of a long chain, moving it around a bit, then dropping it back to re-connect at the tail end of the chain.
It also demonstrates a little snippet of science called eddy currents. Watch how slowly the magnet falls through the aluminum tube compared to falling through air: the falling magnet generates an electrical current in the tube, and that current in turn generates a magnetic field that opposes the movement of the magnet, slowing it down dramatically.
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