[SI-LIST] Re: heat v. radiation Re: FEM/BEM/MoM
- From: "Lin Li" <lilin@xxxxxxxxxxxxx>
- To: <walldrug1316mi@xxxxxxxxx>
- Date: Fri, 29 Aug 2003 16:02:47 -0400
Of course there is inductance and resistance in real world.
But L does not dissipate energe, it only store energy. In this case, L will
repeat the process of store and release energy, or oscillating, and finally
store zero energy.
The lost energy is dissipated by heat and radiation (if no physical damage
or chemical change involved). That is it. There should be no 'paradox' any
more.
Best,
Lin
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Michael Sachtjen
Sent: Friday, August 29, 2003 11:54 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: heat v. radiation Re: FEM/BEM/MoM
Rather it's heat v. radiation has nothing to do with
the "paradox." Even an electrical engineer cannot do
a transient circuit analysis as it was described
below. Without any lossy elements there is no way to
calculate voltage or current over time. The paradox
(more of a fallacy) comes from looking at the starting
point and the ending point without looking at what
happened in between. You could have the same heat v.
radiation discussion about any circuit and any
stimulus; that's not the point.
Where did the 1/4 Joule go? It was dissipated in the
inductive and resistive elements obmitted in the
problem statement. The point is, you cannot omit
them; they are not negligible. If physically you have
two caps and a switch, electrically you have much
more.
- Mike
--- "Pratt, Gary" <gary_pratt@xxxxxxxxxxx> wrote:
> Lets just say the energy is lost to radiation (heat
> (infrared), RF,
> visible (fire and/or arc), sound, etc). Then
> everyone is correct ...
> Unless ... Any energy lost to chemical changes (or
> gained through
> fire)? Any energy transformed to mass, or mass to
> energy? sub-atomic
> effects? These questions, I will gladly defer to
> the physicists.
>
>
>
> -----Original Message-----
> From: Lin Li [ mailto:lilin@xxxxxxxxxxxxx
> <mailto:lilin@xxxxxxxxxxxxx> ]
>
> Sent: Thursday, August 28, 2003 4:18 PM
> To: Feldman, Richard
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: heat v. radiation Re:
> FEM/BEM/MoM
>
>
> 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
> <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
> <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
> <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>
> > < 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
>
>
=== message truncated ===
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