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K0CQ > TECHNI 23.09.08 00:03l 32 Lines 1170 Bytes #999 (0) @ WW
BID : 49067_W0AK
Read: GUEST
Subj: Re: Inductance of a straight wire
Path: IZ3LSV<IW0GPS<CX2SA<KD4GCA<N9ZZK<WD9EKA<N9NDS<KB0OFD<KQ0I<W0AK
Sent: 080921/2148Z @:W0AK.#CIA.IA.USA.NOAM #:49067 [Des Moines] $:49067_W0AK
From: K0CQ@W0AK.#CIA.IA.USA.NOAM
To : TECHNI@WW
> Hello to the technical minded,
> The formula for inductance of a straight round wire is this, for length
> and wire diameter in millimetres (LN is natural logs).
> Microhenrys = 0.0002*Length*(LN((4*Length)/Wire_diameter)-0.75)
> The 0.0002 number become 0.00508 for the ancient inch measurements and
> 0.002 for centimetres.
> Can anyone tell me where this formula originated please. i.e. Who devised
> it, and when and where it was first published.
> 73's from Ralph VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
Took a little digging. I was thinking a US NBS publication I
thought number 74 from about 1921. But searching on the internet
I found an earlier NBS bulletin from 1908. By Edward B. Rosa,
titled "The Self and Mutual Inductances of Linear Conductors,"
Bulletin Bureau of Standards vol 4 # 2 pp 301-344 (1908). Its on
line at g3ynh's web site, specifically at
http://g3ynh.info/zdocs/refs/Rosa1908.
Many internet articles on the inductance of a wire reference Rosa
1908. Even quite recent publications, patents, and theses.
73, Jerry, K0CQ @ W0AK.#CIA.IA.USA
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