Magnet

Magnetic potential of a magnetized material

In Coulomb gauge, the potential due to a magnetized magnet Ω is given by

𝐀(𝐫)=𝜇04𝜋Ω𝐌(𝐫)׈𝖗𝔯2𝑑𝜏=𝜇04𝜋𝜕Ω𝐊𝑏(𝐫)𝔯𝑑𝑎+𝜇04𝜋Ω𝐉𝑏(𝐫)𝔯𝑑𝜏

where 𝐌 is the magnetization, and 𝐊𝑏 and 𝐉𝑏 are the surface and volume bound current densities respectively given by

𝐊𝑏(𝐫)=𝐌(𝐫)׈𝐧𝐉𝑏(𝐫)=×𝐌(𝐫)

If additional free current is present, the principle of superposition may be used to combine the potentials due to free current and due to magnetization (i.e. bound current).

Derivation

Applying ^GE5

𝐀(𝐫)=𝜇04𝜋Ω𝐌(𝐫)׈𝖗𝔯2𝑑𝜏=𝜇04𝜋Ω𝐌(𝐫)×[𝔯1]𝑑𝜏=𝜇04𝜋Ω𝐌(𝐫)×𝑑𝐚𝔯𝑑𝜏+𝜇04𝜋Ω×𝐌(𝐫)𝔯𝑑𝜏

as required.


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