A ferromagnet exposed to two fields at the same time?

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Discussion Overview

The discussion centers around the behavior of a ferromagnetic material, specifically a piece of iron, when subjected to two opposing magnetic fields simultaneously. Participants explore the implications of the fields' strengths and the material's coercivity on its magnetization state, considering both theoretical and practical aspects of magnetization in ferromagnets.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether the magnetization of the iron remains constant when a second opposing magnetic field is introduced, noting the strength of the first field is significantly greater than the second.
  • Another participant suggests that the external fields combine additively and proposes that the magnetization would change as the iron moves along the BH curve, potentially decreasing from a higher value to a lower one.
  • A different participant raises a concern about the coercivity of the iron, questioning if the magnetization could indeed reach zero given that both fields exceed the coercivity threshold.
  • One participant posits that increasing the intensity of the magnetic field could lead to the iron becoming a permanent magnet, as the applied field exceeds the coercivity.

Areas of Agreement / Disagreement

Participants express differing views on how the opposing magnetic fields affect the magnetization of the iron. There is no consensus on whether the magnetization remains the same, decreases, or leads to permanent magnetization.

Contextual Notes

Participants reference the coercivity of the iron and the BH curve, but there are unresolved assumptions regarding the saturation state of the magnet and the exact nature of the magnetic interactions.

Who May Find This Useful

This discussion may be of interest to those studying ferromagnetism, magnetic materials, or related fields in physics and engineering, particularly in understanding the effects of competing magnetic fields on material properties.

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A piece of iron is placed in exterior magnetic field(+B1,"Going right"), with H = 100 Oe
At the same time, there is another opposite magnetic field acting on that same iron (-B2,"Going Left") with H = 10 Oe

They oppose each other, the iron is magnetized initially by B1, what happens when the second field is introduced while B1 still exists?
Magnetization stays the same? Since the intensity of the first field(B1) is stronger by a factor of 10, however, the coercivity of that iron material is 0.5 Oe, Magnetization = 0?
That's what is confusing me here... And that's the most important thing
For reference:
BHCurve.gif
 
Last edited:
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It wouldn't stay the same unless the magnet is still saturated at 90. The external fields combine additively so just think of it going form 0 to 100 to 90. So you go somewhere up on the BH curve then probably start moving back down, albeit on a higher trajectory.
 
H1 - H2 = 90 Oe, since they are both vectors, makes sense.
But what does not is the iron core gets magnetized/demagnetized @ 0.5 Oe, if there are values greater than that in both directions, shouldn't magnetization = 0?
 
By increasing the intensity of the field, the iron ferromagnet becomes a permanent magnet?
Since H is beyond the coercivity.
 

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