magnets

Of course you get this result by closing the magnetic circuit with a piece of ferromagnetic material of sufficient section: in this way all the magnetic field lines will be inside the material, and only negligible effects will be present outside.
However, as a permanent magnet normally performs its function in the air gap, your magnet will become useless.
If you can enclose the magnet AND the functional elements into a box of ferromagnetic material, also you won't get any magnetic effect outside. However this is normally impossible: for example if your magnet is used in a loudspeaker, you won't hear anything from it!


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motori@xcalcs.com
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