Magnetic Moment of a Rare-Earth Magnet?

AI Thread Summary
The discussion focuses on calculating the magnetic field at a distance from a rare-earth magnet using the equation B = μ₀ * 2μ / (4πd³). Participants seek an order of magnitude value for the magnetic moment (μ) of rare-earth magnets, specifically neodymium. It is noted that for neodymium magnets, the magnetic moment can be approximated by multiplying the volume by 875 kA/m based on its short-circuit induction of around 1.1T. The conversation also highlights that different types of magnets, like AlNiCo and ferrite, have varying permeability, affecting how their magnetic properties can be calculated. Accurate data for neodymium magnets can be found in provided resources.
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I was trying to find the value of the magnetic field at a distance x from a rare-earth magnet and came across this equation:

B=\mu_o*2\mu/(4\pi*d^3)

Does anyone happen to know the magnetic moment, \mu, of a rare-earth magnet? Nothing specific, an order of magnitude value is fine.

Thank you!
 
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For a neodymium magnet that has permeability near 1 and produces around 1.1T in short-circuit, you could:
multiply its volume by 1.1T/(4pi*10-7)
that is, volume * 875kA/m.

With neodymium, this approximation is not bad. True data there for instance:
http://www.cy-magnetics.com/CY-Mag-NdFeB.pdf
remember 1 G = 100 µT and 1 Oe produces 1 G in vacuum. These were the CGS units.

AlNiCo magnets, as well as iron magnets, have an important permeability, so you can't convert their short-circuit induction to the coercivity as if they were vacuum plus a coil. But with ferrite magnets, the approximation holds more or less.
 
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