Is there any way to coil a wire around a permanent magnetic and apply an electrical current in which a permanent magnet field can be neutralized, increased or reversed? Just like making a simple electromagnet except the iron rod or bolt in the center is replaced with rod made from Earth magnet.
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$\begingroup$ Changing the medium in which which magnets are present changes the "net" attraction force between them. Select a medium with low permeability. See en.wikipedia.org/wiki/Permeability_(electromagnetism) $\endgroup$– user102705Commented Feb 7, 2017 at 18:41
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$\begingroup$ You do realize that the apparent definition of 'attraction distance' here tells you more about the environment the magnets find themselves in than it does about the strength of the fields, right? Grease the surface on which the magnets sit and the distance goes up. Use sand-paper instead and it goes down. Go to micro-gravity and it goes up more (in principle hugely). $\endgroup$– dmckee --- ex-moderator kittenCommented Feb 7, 2017 at 18:57
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A rare earth magnet is "hard": once it's magnetized, it takes a lot of energy to change its magnetization. It's possible, but not easy. Here are some background references: Ref1 Ref2. This reference Ref3 describes experiments in which the magnetic polarization of a rare earth magnet is reversed by application of an external magnetic field. It required a very strong field of 19 Tesla, which is ~20x stronger than the typical field in an MRI machine. A typical rare earth magnet only has a field of ~0.2 Tesla.
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2$\begingroup$ It would require a LOT of wraps and a LOT of current. $\endgroup$ Commented Feb 10, 2019 at 3:12