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The magnet is slowed down when it falls through the complete loop, but since the cut makes the ring incomplete, I'm inclined to think that there will be no induced current in the ring and thus the magnet falls with no change in acceleration.

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  • $\begingroup$ Video comparing magnets falling through unslotted versus slotted copper tube here $\endgroup$ – Hal Hollis Jun 2 '17 at 19:32
  • $\begingroup$ Because we're seen several questions recently that all specify 'copper' in particular I feel I should mention that these behaviors are not specific to copper: they depend on having a conductor and they work better with good conductors than poor ones. Copper is simply chosen to maximize the effect. I do a classroom demo using an aluminum tube. $\endgroup$ – dmckee --- ex-moderator kitten Jun 2 '17 at 20:24
  • $\begingroup$ @dmckee I suspect that, conductor or not, you might struggle to perform this demonstration with a steel tube. $\endgroup$ – Emilio Pisanty Jun 2 '17 at 21:38
  • $\begingroup$ @EmilioPisanty Well, the conductivity of carbon steel is about an order of magnitude lower than that of copper (and stainless is worse), so the effect is smaller by about the same factor. On the other hand aluminum is within a factor of two, which is more than good enough for classroom purposes. You'd do slightly better than copper if you could afford a solid silver tube, but ... $\endgroup$ – dmckee --- ex-moderator kitten Jun 2 '17 at 21:42
  • $\begingroup$ @dmckee No, the point is that you need the tube to be non-magnetic - the magnet will just stick to the side of a carbon-steel tube, and it won't fall ;-). That is, I think, the main impulse for the emphasis on copper. $\endgroup$ – Emilio Pisanty Jun 2 '17 at 21:52

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