# unknown formula

Discussion in 'Electronics Homework Help' started by foTONICS, Oct 20, 2011.

1. ### foTONICS

332
9
Sep 30, 2011
Hey everyone. I have a mid-term next week and I was going through my notes and I came across this formula:

k= M/√(L_1*L_2 )

I believe it has something to do with transformer coupling. L1 and L2 being the first and second transformer. I know that K is a constant, but i am having trouble remembering what the M stands for.

any help is appreciated.

2. ### davelectronic

1,087
12
Dec 13, 2010
My maths is not good, could it be mutual, or mass. Other than that not sure.
Dave.

3. ### foTONICS

332
9
Sep 30, 2011
I found it, M is the mutual inductance between the two transformers

4. ### duke37

5,364
769
Jan 9, 2011
Except that there are not two transformers, only one. There are two windings.

5. ### foTONICS

332
9
Sep 30, 2011
sorry, meant the coils of the two tuned circuits

1,114
159
Aug 13, 2011
It's a version of the mutual inductance formula arranged to solve for the coupling coefficient. M is the mutual inductance; k is the coupling coefficient (0-1).

Last edited: Oct 21, 2011
7. ### Will D

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0
Mar 14, 2012
You are right fo Tonics M is Mutual induction in the formula.