- #1
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A derivation in Stoner's "The Demagnetizing Factors for Ellipsoids"
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SUMMARY
The discussion centers on the derivation of the equation ##H-B = B/(1-D)## from Stoner's "The Demagnetizing Factors for Ellipsoids." Participants clarify that the relation arises from algebraic manipulation of the equation ##H=-D(B-H)##, revealing a missing minus sign in equation 1.6. Additionally, inconsistencies are noted in equation 4.11a regarding the value of ##D_a##, suggesting a potential error in the manuscript. The conversation emphasizes the importance of understanding electromagnetic concepts, particularly the demagnetizing factor.
PREREQUISITES- Understanding of electromagnetic theory, specifically demagnetizing factors
- Familiarity with algebraic manipulation of equations
- Knowledge of Stoner's work in condensed matter physics
- Access to academic papers and resources, such as Ashcroft and Mermin's textbooks
- Review Stoner's "The Demagnetizing Factors for Ellipsoids" for detailed equations
- Study the derivation of demagnetizing factors in electromagnetic theory
- Examine Ashcroft and Mermin's "Solid State Physics" for foundational concepts
- Investigate the implications of typos and inconsistencies in scientific literature
Students and researchers in condensed matter physics, particularly those focusing on electromagnetic properties and mathematical derivations in physics literature.
- #2
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##H=-D(B-H) ##. They got that part right. Let's do some algebra: ##H(1-D)=-DB ##, so that ##H=\frac{-DB}{1-D} ##. Their last equation of 1.6 needs a minus sign. ## \\ ## Note: Equation 1.6 assumes the applied magnetic field ## H_a## is zero. ## \\ ## And I also checked equation 1.7, and it is correct.
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- #3
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To tell you the truth I wasn't sure it's implied from the same relation in (1.6).
I thought to myself that it was some relation from previous work or somewhere else in the article.
Now that I see that's a simple matter of algebra I feel so stupid... D-:
I thought to myself that it was some relation from previous work or somewhere else in the article.
Now that I see that's a simple matter of algebra I feel so stupid... D-:
- #4
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The author did have a "typo" in equation 1.6 (missing the minus sign). I'm glad you posted it. IMO more people should be studying E&M concepts such as the demagnetizing factor. We could use more E&M postings.
- #5
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I kept on reading the paper.
On page 11 in the following attachment in eq. (4.11a) for ##D_a## after the first equality should it be ##3/4\mu^4 \ln (2m)## or as it is written there?
I am asking since after the second equality they write it as ##3/4 \mu^4 \ln (2m)##.
On page 11 in the following attachment in eq. (4.11a) for ##D_a## after the first equality should it be ##3/4\mu^4 \ln (2m)## or as it is written there?
I am asking since after the second equality they write it as ##3/4 \mu^4 \ln (2m)##.
- #6
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It looks to me like it should be 3/2, but I would have to see the previous page. Clearly they have an inconsistency there.
- #7
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It isn't discussed in the previous page.
You can find the article in sci-hub. (I know it's not really legal, but also making ordinary people who are interested in science pay lots of money for papers in science is a rip off).
You can find the article in sci-hub. (I know it's not really legal, but also making ordinary people who are interested in science pay lots of money for papers in science is a rip off).
- #8
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Hi @Charles Link have you kept on reading this article, perhaps?Charles Link said:
I plan to return to Ashcroft and Mermin and Kittel's books once more for my Condensed Matter Physics I, hopefully now I will ace it in this summer!
- #9
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No, I didn't do any additional reading of it.MathematicalPhysicist said:
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