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RE: K Factor & Mutual Inductance



Subject: 
        RE: K Factor & Mutual Inductance
  Date: 
        Thu, 10 Apr 1997 07:54:36 -0400
  From: 
        Heinz Wahl <hwahl-at-jtc-campus.moric-dot-org>
    To: 
        "'Tesla List'" <tesla-at-pupman-dot-com>


John,

        You state that the R is effective, not DC or AC. Why can't you
measure the R of the coil, calculate the XL, at the
expected frequency of operation, and use the result to find a ballpark
Q? Could you elaborate on effective R?

Heinz

>
>
>Hi John, All,
>Have you ever tried the formula Q = sqrt( L / C ) / R.
>
>Barry
>
> ----------------------------------------------------

  Barry -

  I have never seen the above Q factor equation before. What would you
use
for R? In the usual equation   Q = X/R   where X = 6.283 F L  the R is
an
effective resistance, not DC or AC.  The only way to find the R is to
use a
value for a typical Q and X and solve the equation for R. The Q factor
like
the K factor is easily found by tests after the TC is built, however, at
the
design stage these two factors are difficult to determine. 

The basic nature of Q for Tesla coils has to do with the energy stored
in
the field of the coil and the energy dissipated. The Q factor also
involves
resonant rise in voltage and other electrical effects. It is also
interesting that Q involves other phenonmena such as in the swing of a
pendulum and in horological science ( measuring time). 

  John Couture