I've been studying Electromagnetism lately, in which it is clearly stated that magnetic fields are a consequence of electric current. This fact is confusing to me when I apply it to permanent magnets. Please help me understand this.
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2 Answers
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The statement in your course or book - what material are you using? - is incomplete. Magnetism can also be caused by electron spin magnetic moment. In iron permanent magnets the field results from each iron atoms having a magnetic moment due to 5 aligned electron spins. Not only electrons also protons and neutrons have spins. Nuclear spin magnetism is the basis of magnetic resonance imaging. Several more exotic elementary particles also have spin magnetic moments.
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$\begingroup$ I'm currently in 12th class, so that might be the reason for the incomplete definition. $\endgroup$ Commented Aug 19, 2018 at 12:31
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Within magnetized materials, such as a permanent magnet, a magnetization field $\mathbf M$ exists that contributes to the free magnetic field $\mathbf H$ to give the total magnetic field $\mathbf B$: $$\mathbf{B} = \mu_{0} (\mathbf{H + M})$$ $\mathbf{M}$ is caused by either microscopic electric currents resulting from the motion of electrons in atoms, or the spin of the electrons or the nuclei of the atoms in the material, which creates a "bound current".
answered Aug 19, 2018 at 9:05