[SI-LIST] Re: heat v. radiation Re: FEM/BEM/MoM
- From: "Lin Li" <lilin@xxxxxxxxxxxxx>
- To: "Feldman, Richard" <rfeldman@xxxxxxxxxxx>
- Date: Thu, 28 Aug 2003 17:18:16 -0400
Richard,
You are absolutely right.
I drew my conclusion based on assumption that impedance is negligible which
is likely the real situation.
If the circuit is not that lossy, then most energy is lost by radiation
eventually if it could be.
Thanks for your comment!
Lin
-----Original Message-----
From: Feldman, Richard [mailto:rfeldman@xxxxxxxxxxx]
Sent: Thursday, August 28, 2003 3:19 PM
To: lilin@xxxxxxxxxxxxx; gary_pratt@xxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: RE: [SI-LIST] heat v. radiation Re: FEM/BEM/MoM
Lin, I respecfully disagree with your statement.
The lost energy can be partitioned arbitrarily
between heat and electromagnetic radiation,
depending on the circuit's geometry, R, and L values.
It's trivial to do the experiment and get mostly heat.
But I'm guessing that with some design effort,
one could get mostly radiation.
The transient behavior after switch closure is
generally oscillatory, damped according to losses.
Rich
> -----Original Message-----
> From: Lin Li [mailto:lilin@xxxxxxxxxxxxx]
> Sent: Thursday, August 28, 2003 12:31 PM
> To: gary_pratt@xxxxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: FEM/BEM/MoM
>
>
> Heat transformation is not likely to happen unless the switch
> cable has very
> large resistance.
>
> We know at the moment of the electrons transfer, there will
> be a transient
> which will induce radiation. That is where the energy goes.
>
> I cannot deny heat effect but it is minor.
>
> Best,
>
> Lin
> **********************
> Lin Li
> Ph.D. candidate
> 3123 Glenn Martin Hall
> Mechanical Engineering
> University of Maryland
> College Park, MD 20742
> Ph: 301-405-5588
> ***********************
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Pratt, Gary
> Sent: Thursday, August 28, 2003 1:08 PM
> To: arafi001@xxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: FEM/BEM/MoM
>
>
> The quarter-Joule turns into heat when the switch is vaporized into a
> cloud of smoke.
> Whats the paradox?
>
> Gary L. Pratt, P.E.
> Product Manager
> High-Speed Design Kits
> Mentor Graphics
> (503) 685-1177
> gary_pratt@xxxxxxxxxx
>
>
>
>
> -----Original Message-----
> From: Abdulrahman Rafiq [ mailto:arafi001@xxxxxxx
> <mailto:arafi001@xxxxxxx> ]
> Sent: Thursday, August 28, 2003 12:36 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] FEM/BEM/MoM
>
>
> Geoff,
>
> Could you ellaborate on this a little more, as I am afraid i
> can't quite see what happened to the 1/4 Joule of energy.
> Perhaps if you could do a quick back of the envelope
> calculation as an example.
>
> -----------------
>
> Just a little diversion to show the error in a schematic:
> An old example often quoted is the problem of connecting two
> one farad
> capacitors together by a switch; one is at 1V potential, the
> other zero.
> The initial energy is 1/2 CV**2 =3D 0.5 joule. After closing
> the switch th=
> ere
> is charge distribution, and energy =3D 1/8 +1/8 =3D 0.25
> joule. Where did =
> the
> missing 0.25 joule go? If you did an electrical degree,
> you'd see the
> paradox. If you studied high frequencies, you'd know the
> answer. (I did a
> Physics degree, then built RF circuits, so for me a capacitor
> is not a
> capacitor.)
>
> The answer is
> 1) it's not physically possible to put two capacitors
> together at one point
> 2) therefore they are separated by a distance
> 3) therefore on closing the switch, the discharge current
> travels a distance
> 4) the conductors have finite conductivity
> 5) therefore there is a varying electromagnetic field and
> energy is
> dissipated and radiated
> 6) please don't talk about too much about inductance because
> it's only an
> approximation.
> -------------------
> ---------------------------------------
> Abdulrahman Rafiq
> Department of Physics
> University of California
> Riverside, Ca. 92521
> Email: arafi001@xxxxxxx
> URL: www.geocities.com/arafiq786
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
