Re: New Inductance Formula

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
> 
> Inductance is defined as the flux linkages divided by the current causing
> the flux or
> 
>    L = A/I
> 
> Refer to page 538 the Electromagnetics Problem Solver by Dr. M. Fogiel,
> 1983, Research and Education Association.
> 
> John Couture
> 
> ----------------------------
> 
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Sunday, April 28, 2002 9:14 AM
> To: tesla-at-pupman-dot-com
> Subject: RE: New Inductance Formula
> 
> Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <dave-at-volantis-dot-org>
> 
> Hi Ed,
> 
> >Wheeler's formulae (there are several) are usually known as Wheeler's
> approximations, and were developed during "slide rule days" as a convenient
> and simple tool for radio engineers, who seldom need an accuracy of as great
> as 1%.
> 
> Wheeler's formulas have served us well for quite a while.  I'm not disputing
> that nor am I disrespectful of his contribution.
> 
> >Quite recently a guy named Lundin (?) worked out fairly simple expressions
> giving an accuracy of better than a part in 300,000.
> 
> I'd like to see that formula.  If you or anyone else knows where to find it
> please post it to the list.
> 
> >By the way, I believe the dimension of inductance is indeed length,
> (centimeters in the old cgs system) though don't have time to look that up
> right now.
> 
> The dimensions of inductance in the MKS system are kg*m^2/coul^2.  In the SI
> system it is kg*m^2/s^2*A^2.  In the cgs system it is sec^2/cm.
> 
> Dave
Tesla list wrote:
> 
> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
> 
> Inductance is defined as the flux linkages divided by the current causing
> the flux or
> 
>    L = A/I
> 
> Refer to page 538 the Electromagnetics Problem Solver by Dr. M. Fogiel,
> 1983, Research and Education Association.
> 
> John Couture

	Not sure what A represents in your expression, but it seems to fit very
well with the definition I learned in physics class longer ago than I
want to think of.

	Inductance = flux linkages per unit current

which appears to be the same if A represents flux linkages.

 
> The dimensions of inductance in the MKS system are kg*m^2/coul^2.  In the SI
> system it is kg*m^2/s^2*A^2.  In the cgs system it is sec^2/cm.
> 
> Dave

	If you plug the MKS and SI definitions into the formula for stored
energy (1/2 L I^2) you get the units kg * (m/s)^2, which has the right
form.  Can't do it for cgs until I consult my physics books at work.

Ed