Magnetic Moment of a Rare-Earth Magnet?

Click For 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.
fasc
Messages
1
Reaction score
0
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!
 
Physics news on Phys.org
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.
 
I'm working through something and want to make sure I understand the physics. In a system with three wave components at 120° phase separation, the total energy calculation depends on how we treat them: If coherent (add amplitudes first, then square): E = (A₁ + A₂ + A₃)² = 0 If independent (square each, then add): E = A₁² + A₂² + A₃² = 3/2 = constant In three-phase electrical systems, we treat the phases as independent — total power is sum of individual powers. In light interference...

Similar threads

  • · Replies 15 ·
Replies
15
Views
5K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 13 ·
Replies
13
Views
3K
Replies
6
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
2
Views
2K
  • · Replies 52 ·
2
Replies
52
Views
8K
  • · Replies 7 ·
Replies
7
Views
13K
  • · Replies 13 ·
Replies
13
Views
2K
Replies
2
Views
2K