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I recently encountered the following practical problem. We have a system of several layers:

  1. a neodymium magnet; a disc, dimensions and grade to be determined
  2. 1 mm of 925 sterling silver; we can suppose that this is a disc, diameter 15 mm
  3. 0.5 mm of paper or tissue (cotton)
  4. 1 mm of the same silver disc
  5. again, a neodymium magnet

How can I estimate the attraction force between these two magnets in this system based on their dimensions and grade? I found several estimators online (this one, for example) but they all assume that there is nothing between the magnets.

Even being able to estimate "X mm in diameter and Y mm in thickness would yield at least Z grams of pull" would be great.

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    $\begingroup$ As long as the stuff in between is non-magnetic (which yours is) then the force will be the same... you have to plug in your distance. (2.5 mm) $\endgroup$ – George Herold Jul 31 '15 at 18:48
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    $\begingroup$ The calculator you link to has the information you want. The 'magnet to magnet' calculation takes into account the separation distance. The term 'magnet to magnet' is used to distinguish from the case of the magnet being near some other object (such as a steel plate), but doesn't necessarily mean that there is no separation between the two magnets. $\endgroup$ – Chris Mueller Jul 31 '15 at 21:10
  • $\begingroup$ As general as this is, it would be better handled on Physics SE. Bring your vector field calculus books and Maxwell's equations. $\endgroup$ – Phil Sweet Feb 21 at 1:50
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It is not changed unless the items between are ferromagnetic. Dennis #neomagman

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    $\begingroup$ I think it depends on the permeability, but you are right that the permeability of the ordinary, non-ferromagnetic materials is close to 1. $\endgroup$ – peterh Sep 22 '20 at 23:05
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    $\begingroup$ I suggest elaborating on response. $\endgroup$ – Mahendra Gunawardena Sep 23 '20 at 10:55

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