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Re: [Phys-L] breaking magnets

On 05/04/2014 01:28 PM, Ken Caviness asked:
is the force at any given distance provided by the combination of 2
disc magnets on some object = twice the force of one disc magnet at
the same distance on the same object? Or is it greater/less than
twice the force of one disc magnet? My quick and dirty model says
"=", but "slightly greater" wouldn't surprise me.

That's ill posed!

The "force at any given distance" is not simply a function of
distance; it depends on angle.

In particular, there will be some points where the field due
to the two-disk stack is zero, even though the field due to
either disk separately would be nonzero. This happens near
the equator of the two-disk stack.

Hint: Model each disk as a simple current loop.