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If a bar magnet is spun about its north-south axis, an electric field is produced, which is directed radialy outward in all directions. As the length of the north-south axis is reduced, while keeping the strength of the magnetic field the same, this electric field becomes more and more sphericaliy symetric.

Since a magnetic field is the effect of a relatively moving electric field and an electric field is the effect of a relatively moving magnetic field, each can be derived from the other, why is the one that has a monopole (electricity), thought of as the more 'fundamental' of the two?

Is it possible that electric monopoles may in fact be due to 'spinning' magnetic fields?

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    $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Commented Jan 27, 2023 at 6:01

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If a bar magnet is spun about its north-south axis, an electric field is produced, which is directed radialy outward in all directions.

This description should be supplemented by the description of electromagnetic induction (including the Lorentz force and the Hall effect). A changing magnetic field causes the movement of electrons, practically in a conductive wire. Due to the alternating influence of the rotating bar magnet, the electrons in a conductor are thus moved back and forth. This creates an alternating current. And an inevitable loss of power due to electromagnetic radiation as a result of the interaction between the magnetic field of the bar magnet and the magnetic dipoles of the influenced electrons.

Since a magnetic field is the effect of a relatively moving electric field and an electric field is the effect of a relatively moving magnetic field, each can be derived from the other, why is the one that has a monopole (electricity), thought of as the more 'fundamental' of the two?

This is an artefact from the time of the discovery of the magnetic dipole of the electron. It was inconceivable that an electron could be both an electric charge and a magnetic dipole. Today, this does not prevent us from considering both fields as fundamental for the electron.

And it is indeed the case that you get a measurable (macroscopic) electric field simply by separating charges - electron surplus on the one side and electron deficiency on the other - and a magnetic field by the alignment of the magnetic dipoles of the influenced electrons.

Is it possible that electric monopoles may in fact be due to 'spinning' magnetic fields?

It does not rotate. That was an earlier explanation that is completely irrelevant today. See the explanation above, in which both fields are part of the electron and the separation dr charges or alignment of the magnetic dipoles lead to the macroscopic fields.

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  • $\begingroup$ Suppose you have two bar magnets, each hanging by their north poles from the ceiling by a thread, a distance d apart, and let their south poles likewise be attached to the floor by two threads. You thus have two straight bar magnets on two parallel lines a distance d apart. They tend to repel each other with a force f in this configuration. Now twist one thread rapidly in a positive sense and twist the other thread in a negative sense so that each magnet is spinning with its thread as its axis. How does the force f change as a function of the speed of this twisting and why? $\endgroup$
    – pete
    Commented Jan 28, 2023 at 21:46

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