Deconstructing Kitty

Re:Deconstructing Kitty by abetusk on Tuesday May 22, 2018 @11:59AM (#17126907)

An interesting tidbit talking about the coil used to push the magnet at the end of the bob (the internal mechanism of the kitty hand):

    Why does the coil use air core rather than something
    like iron that would concentrate the magnetic field?

    Because then the magnet would want to stick to it.

Is there a nonmagnetic material that could be used to concentrate the magnetic field? Aluminum?

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Re:Deconstructing Kitty by lmm on Tuesday May 22, 2018 @12:11PM (#17127002)

I'm only going by what I just read on https://en.wikipedia.org/wiki/Magnetic_core , but it seems like a core only works by being magnetic itself. Note that "air core" is a term of art; if there's a nonmagnetic (e.g. plastic or ceramic) core it's still called "air core".

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Re:Deconstructing Kitty by blattimwind on Tuesday May 22, 2018 @01:35PM (#17127791)

Copper being diamagnetic has a very low magnetic permeability, basically the same as air, but now you have an eddy current brake.

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