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Comment by digitalsushi | Hacker News Reader

Without using any math, I believe it would be a safe assumption that between the pause of reloading the magnet manually and the heat his hand would absorb by grabbing the pipe, heat would never accumulate beyond the ambient temperature in the pipe. However, it would be delightful to hear why I am wrong, since it would be very interesting.

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You are correct - there's really not that much energy being converted to electric current, much less being converted from current into heat through the resistance of copper.

I would be interested in hearing what would happen if the pipe was a superconductor, though - would the induced current be so strong that the magnet wouldn't drop at all?

Superconductors have some special-case behavior with regard to magnetic fields:

http://en.wikipedia.org/wiki/Superdiamagnetism

You mean...somewhat like this?

http://www.physorg.com/news/2011-10-quantum-levitating-video...

Only somewhat; it's a different set-up, of course.

Yes. It would hang there. That was one of the demonstrations of why superconductors are so cool back in the day. I remember seeing those nitrogen(I think) liquid cooled super conductors holding a magnet above them.

I don't think so. If I remember the explanation, superconductors "block" magnetism, rather like having another magnet with the same pole opposed. In that case, the magnet would probably just fall as though the tube was made of plastic or other non-conductor. (Just speculation, it has been several years since I read about superconductivity).

They are diamagnetic i believe (so is water' very weakly so. - google for levitating frogs for a laugh.)

Diamagnetic materials create an equal field to what they are exposed to... Causing repulsion. In the case of superconducting, the field generated is very strong and why we can levitate any old magnet over a superconductor.

Levitating a frog (mostly water right?) takes some incredibly strong fields..... Liquid cooled bitter magnets etc....

Side note - rare earth supermagets are toxic. When they shatter, you dont want to ingest any of the bits/dust

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