Understanding that questions similar have been asked, I wanted to propose a different one.

Imagine you make a circle of 'permanent' magnets where each magnet has the N direction pointing inward at an angle of say 30 degrees from aligned with the center of the circle. The number of these magnets I believe would be relatively irrelevant once you get like 10 or so magnets in a circle. Now imagine there is a pinwheel of permanent magnets floating on some oil or liquid. The magnets in the pinwheel have their N facing out towards the edge of the circle. This should generate a force to spin the pinwheel as I understand due to repulsion of the two magnet ends. Assuming there is a speed such that this device can keep spinning, how would such a mechanism eventually be forced to come to a stop?


1 Answer 1


Both wheels will have symmetrical magnetic fields with a repeating field contour (alternating maxima and minima at a given radius) around the perimeter. In a frictionless environment, a maximum in the field of the outer ring will repel the nearest maximum of the inner ring, but only until the inner ring's maximum comes closer to the next outer maximum, which repels it back. So the inner ring would oscillate back and forth rather than spinning.

Now if you apply any load, including friction, the oscillation dampens until the inner ring stops moving entirely. No free lunch here.


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