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Re: K Quiz
Subject: Re: K Quiz
Date: Fri, 23 May 1997 11:37:08 -0400 (EDT)
From: msr7-at-po.cwru.edu (Mark S. Rzeszotarski, Ph.D.)
To: Tesla List <tesla-at-pupman-dot-com>
Hello coilers,
I posed a question about how K changes as the
primary and secondary coils are modified, to which
Bob Schumann responded:
>I do not have enough data to make a determination
>to fill in missing K values. Though you have
>stated M for the first setup, it is missing for
>all the others. I can not solve for K without
>the known value of the variable M.
While true, by knowing the geometry and the
method by which M arises, one can predict
the solution (as proven by an off-list response
I have already received).
> You said assume the primary
>and secondary coils <are> aligned on a flat plane.
>If there is a way to calculate M from this
>geometry, I am not aware of it. IMO as soon as
>you change out 1 coil for another, the field
>interaction changes and M must be re-calculated
>prior to solving the coefficient of coupling.
Yes, M changes whenever either coil changes.
Mathematically, M can be determined by computing
the line integral of the paths of little dl line segments
along both Ls and Lp. This is known as Neumann's
formula, and can be found in physics texts. I have
implemented this on a computer, and it works,
although it is incredibly slow to compute. By thinking
about the preceding sentences and the relationship
between K, M, Lp and Ls, one can arrive at the
correct answer without explicit knowledge of M.
>I've got my flame-proof suit on so have at it! Heheh
No flames. I had the same thoughts until I took
a look at it through simulation and demonstration in
the lab to prove the math was right!
I'll post the answer on Tuesday or Wednesday.
Regards,
Mark S. Rzeszotarski, Ph.D.