# A derivation in Stoner's "The Demagnetizing Factors for Ellipsoids"

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## Main Question or Discussion Point

In the attachment in eq. (1.6) I don't understand why is ##H-B = B/(1-D)##?

Where does this relation come from?

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Homework Helper
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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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Delta2 and MathematicalPhysicist
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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-:

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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.

Delta2 and dRic2
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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)##.

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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.

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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).

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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.

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!