[TCML] Reality or Artifact

[mddeming@xxxxxxx]

Hi All,
 
In the classic, quick and dirty formula for the calculation of solenoid inductance, 
 
L=(Nr)^2/(9r+10h) 
it can be shown with a little Calculus and Algebra that the maximum inductance for a given length of wire occurs when h=0.9r. This formula was originally derived, however, for "long" solenoids but the calculation results in what may be described as a rather "short" solenoid. The maximum may be an artifact of the approximation. Does anyone know the range over which the formula is valid and if there is an actual maximum at or near this ratio (h/d = 0.45)? If not, I suppose numerous iterations of Javatc could be plotted, but there again, what is validity range of Javatc's approximations? Perhaps the next step would be for me to bring the question to the "High-Mages" of TSSP.

Matt D.




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