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

## 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 text book, with the red oval area being the part that I'm totally confused about

## 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

I can't sleep scratching my head T_T
Thanks a bunch!

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cnh1995
Homework Helper
Gold Member
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.

gneill
Mentor
Note the division operator:

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.

cnh1995
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 :(