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Mediocrates
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So are there photons "flowing" from one end of a permanent magnet to the other? If so what determines the frequency?
The exchange effect is an additional effect necessary to explain ferromagnetism, but the magnetic surface currents can be quantified with what I believe are highly accurate results. For a simple calculation, see the following post: https://www.physicsforums.com/threads/magnetic-field-of-a-ferromagnetic-cylinder.863066/ Hopefully this doesn't start to lead too far off topic before the OP gets a chance to respond. ## \\ ## Also, Griffith's Electrodynamics book contains a very good derivation of the surface currents as he computes the vector potential ## \vec{A} ## from an arbitrary distribution of magnetization ## \vec{M} ##. I believe this result is in section 6.2 of his book.rumborak said:@Charles Link , that is an engineering approximation that hardly elucidates the actual generation of the magnetic field in a permanent magnet.
Charles ... you are making this far more complex than what a B level topic should beCharles Link said:The exchange effect is an additional effect necessary to explain ferromagnetism, but the magnetic surface currents can be quantified with what I believe are highly accurate results. For a simple calculation, see the following post: https://www.physicsforums.com/threads/magnetic-field-of-a-ferromagnetic-cylinder.863066/ Hopefully this doesn't start to lead too far off topic before the OP gets a chance to respond. ## \\ ## Also, Griffith's Electrodynamics book contains a very good derivation of the surface currents as he computes the vector potential ## \vec{A} ## from an arbitrary distribution of magnetization ## \vec{M} ##. I believe this result is in section 6.2 of his book.
How would one determine the existence of a field in the absence of particles?weirdoguy said:Nothing. Field is a field, entity that lives on it's own. Photons are "excitations" (whatever that means) of quantum electromagnetic field, but that doesn't justify the claim that em field is composed of anything.
Quess my question was, "can there be a field without a particle?" I thought particles give rise to fields?rumborak said:That's probably more of a philosophical question since that scenario wouldn't be our universe.
Mediocrates said:I thought particles give rise to fields?
A magnetic field is made up of invisible lines of force that surround a magnet or current-carrying wire. These lines of force are created by the movement of electrically charged particles, such as electrons.
A magnetic field is created when electrically charged particles, such as electrons, move. This movement can be the result of either a permanent magnet or an electric current.
Most materials can be affected by a magnetic field to some degree. However, materials that contain iron, nickel, or cobalt are the most strongly influenced by magnetic fields.
Yes, magnetic fields can be shielded or blocked by certain materials. For example, materials such as iron or steel can act as a shield against magnetic fields, as they are able to redirect the lines of force away from the protected area.
The strength of a magnetic field can vary depending on the distance from the source, the size of the magnet or current-carrying wire, and the material the field is passing through. The strength of a magnetic field is measured in units of Tesla (T) or Gauss (G), with 1 T equaling 10,000 G.