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Re: Wireless Energy Transmission
Not to get hung up, but Terry was right.. 377 ohms (120pi) is the Impedance
of Free Space, the permittivity (aka the dielectric constant) of free space
(or air) is 1 (in relative terms) and approximately 8.85E-12 F/m in
absolute units.
The propagation speed of electromagnetic radiation (light, radio, etc.) is
c= 1/sqrt(epsilon *mu) where mu is permeability (magnetic property) and
epsilon is the permittivity (electric property). Mu for free space is
defined as 4*pi*1e-7 Tesla*meter/Amp
The impedance is the ratio between voltage and current (Z=E/I) or in more
fundamental properties, the ratio between electric and magnetic fields.
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> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Wireless Energy Transmission
> Date: Friday, May 21, 1999 5:19 AM
>
> Original Poster: Ed Phillips <evp-at-pacbell-dot-net>
>
> Tesla List wrote:
> >
> > Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
> >
> > Yes it is! 120*pi ohms... I was typing fast from memory. I work with
50
> > ohm stuff all day long and I just... :-)
> >
> > Terry
> >
> > At 11:55 AM 5/19/99 -0400, you wrote:
> > >Hi Terry, All,
> > > Isn't air close to a vacuum which is close to 377 Ohms?
> > >
> > >----- Original Message -----
> > >From: Tesla List <tesla-at-pupman-dot-com>
> > >To: <tesla-at-pupman-dot-com>
> > >Sent: Tuesday, May 18, 1999 8:55 PM
> > >Subject: Re: Wireless Energy Transmission
> > >
> > >
> > >Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
> > >
> > >Since the air has an intrinsic impedance of ~50 ohms
> > >
> > >Terry
> > >
> > >
>
> Actually, that's the permittivity (permitivity) of free space, and is
> almost identical for air.
>
> Ed
>
>