Can't understand why the unit of Reluctance is At/Wb

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Homework Help Overview

The discussion revolves around understanding the unit of Reluctance in the context of magnetism, specifically why it is expressed as At/Wb rather than (At/Wb)m2. The original poster expresses confusion regarding the cancellation of units and the derivation of the final expression.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to derive the unit of Reluctance and questions the disappearance of the m2 term in their calculations. Some participants draw analogies between reluctance and resistance in electrical circuits, suggesting a conceptual framework for understanding the relationship between the terms.

Discussion Status

Participants are exploring the mathematical reasoning behind the unit of Reluctance, with some providing clarifications about the division of units. The original poster expresses gratitude for the insights received, indicating a productive exchange of ideas.

Contextual Notes

The original poster mentions a textbook reference and expresses a need for further review of algebraic concepts, suggesting a potential gap in foundational understanding that may affect their grasp of the topic.

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Homework Statement


I can't figure out why the unit of Reluctance is At/Wb and not (At/Wb)m2
This is what I have from my textbook, with the red oval area being the part that I'm totally confused about
Untitled.png

Homework Equations

The Attempt at a Solution


So the m/m cancels out to 1 making it
R=1/(Wb/At·m2)
which is = (At·m2)/Wb
then I have no idea what happened so that m2 vanished and R became At/Wb

Please help me clear up my confusion
I can't sleep scratching my head T_T
Thanks a bunch!
 
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road2knowledge said:
I can't figure out why the unit of Reluctance is At/Wb and not (At/Wb)m2
As your book says, reluctance is analogous to resistance in electrical circuits. Similarly, flux is analogous to current and mmf (Ampere turns) is analogous to voltage.
 
Note the division operator:
upload_2016-5-6_8-5-30.png

The underlined bit is in the denominator of the denominator, so to speak. Hence it can be "promoted" to the numerator of the overall expression.

upload_2016-5-6_8-11-58.png
 
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gneill said:
Note the division operator:
View attachment 100341
The underlined bit is in the denominator of the denominator, so to speak. Hence it can be "promoted" to the numerator of the overall expression.

View attachment 100342
OHHHHHHH!
Thank you so much!
I think I'll need to go back to secondary algebra for a bit of revision :(
 

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