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Q & A: focusing magnetic fields

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Most recent answer: 04/20/2016
If it is possible to guide magnetic field lines using a shaped magnetic material (cone) increasing magnetic density or field strength and the increase in magnetic field strength is proportional to the ratio of the areas of the two ends of the cone. If a cone of magnetic material of 45 degrees with 1 inch at the top and 10 inches at the bottom was held in the air or placed on the ground and earths average magnetic strength is .45 gauss It seems theoretically ignoring edge effects and assuming a uniform initial field I would have a reading of 4.5 gauss at the top of the cone... What is your opinion ? or is there anyone or any research material on strengthening or focusing earths magnet field?
- Greg (age 42)

Truncated cone-shaped pole pieces are routinely used with electromagnets to get higher field strengths, just as you propose. In principle the same method should work with the Earth's magnetic field. One technical problem is that typical magnetic materials don't respond very much to small fields. It would take an especially "soft" magnetic material to properly polarize in response to the small Earth field.

Mike W.

(published on 04/20/2016)

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