Magic capacitors!
in [Design]
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From: The Phantom on 21 Jul 2010 17:57 On Wed, 21 Jul 2010 15:56:02 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"The Phantom" <phantom(a)aol.com> wrote in message news:2cie4650u0spseb6pb1rhs9oaed2eh6hk2(a)4ax.com... >> In the R = 0 case, L is not zero and the energy is lost by radiation. See: > >The presumption is radiation is able to leave. That's the presumption I made. Until you just now said so, nobody said we were inside a superconducting box. >Expressing radiation as a lumped constant equivalent series resistance, assume zero ESR. In other words, inside a superconducting box, so there is no way to measure the resonance (it's a theoretical problem, that's okay) and it resonates forever. > >Tim
From: John Larkin on 21 Jul 2010 18:47 On Wed, 21 Jul 2010 16:30:20 -0500, "George Jefferson" <phreon111(a)gmail.com> wrote: > > >"Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote in >message news:rcie465itdu34iaajm1itdqslepu2i87r6(a)4ax.com... >> On Wed, 21 Jul 2010 12:14:04 -0700, John Larkin >> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Wed, 21 Jul 2010 12:17:41 -0500, "George Jefferson" >>><phreon111(a)gmail.com> wrote: >>> >>>> >>>> >>>>"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >>>>message >>>>news:dj7e465sga7fe3nq7hfl3f0uk601pvrem8(a)4ax.com... >>>>> On Wed, 21 Jul 2010 11:19:31 -0500, "George Jefferson" >>>>> <phreon111(a)gmail.com> wrote: >>>>> >>>>>> >>>>>> >>>>>>"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >>>>>>message >>>>>>news:s43e46la1p1vt11527eg3ptl9ulm44dfrj(a)4ax.com... >>>>>>> On Wed, 21 Jul 2010 07:54:03 -0500, "George Jefferson" >>>>>>> <phreon111(a)gmail.com> wrote: >>>>>>> >>>>>>>>Suppose you have two capacitors connected as >>>>>>>> >>>>>>>>--*-- >>>>>>>>| | >>>>>>>>C1 C2 >>>>>>>>| | >>>>>>>>----- >>>>>>>> >>>>>>>>where * is a switch. >>>>>>>> >>>>>>>>What is the total energy before and after the switch is closed(in >>>>>>>>general). >>>>>>> >>>>>>> Energy is conserved, so it's the same, if you account for all the >>>>>>> manifestations of energy. >>>>>>> >>>>>> >>>>>>You didn't answer the question. I assume this because you don't know. >>>>>> >>>>> >>>>> State the question unambiguously and I will. >>>>> >>>>> As I said, the puzzle is both ancient and trivial, so probably JT >>>>> invented it. There are web sites and even academic papers devoted to >>>>> it. Given all that, how could I not understand it? >>>>> >>>> >>>>Um you don't get it. Your ignorance in basic electronics amazes me. >>> >>>That's funny. But people can choose to be amazed in all sorts of ways. >>> >>> >>> Michael >>>>got it(although he didn't explain where the energy went but I think gets >>>>it). >>>> >>>>Assume the second cap is initially "uncharged" and has the same >>>>capacitance >>>>as the first. >>>> >>>>Then the initial energy is >>>> >>>>Wi = 1/2*C*V^2 >>>>Wf = 2*1/2*C*(V/2)^2 = 1/4*C*V^2 = 1/2*Wi >>>> >>>>Hence the final energy of the system 1/2 what we started with. >>> >>>Miraculous calculation. Yours and about 300 web sites that admire this >>>puzzle. >>> >>>You didn't wxplain where the energy went - see those 300 web sites - >>>but you are assuming losses. Another solution is that no energy is >>>lost, and it rings forever, in which case the final state that you >>>cite never happens. The exact waveforms are actually interesting. >>> >>>> >>>>I'd really like to hear your explanation but I know thats impossible(as >>>>you'll steal someone elses). After all your the one that believes charge >>>>isn't conserved... heres your change to *prove* it. >>>> >>>> >>>> >>> >>>Check my previous posts. I noted the exact waveform across a resistive >>>switch, for any values of C1 and C2, and an independent way to compute >>>the energy lost in that switch. >>> >>>Given an inductor, one can move all the energy from one charged cap to >>>another, uncharged one. If the C values are unequal, the C*V (charge) >>>on the first cap obviously becomes a different C*V on the second one. >>>I noted that here some weeks ago, too. >>> >>>This is all EE101 stuff. >>> >>>John >> >> Let the hedging begin... >> >> In Message-ID: <3b893612tjjndo8o4v1evro050nonjgp41(a)4ax.com> >> >> You said: >> >> "Right. If you dump all the energy from one charged cap into another, >> discharged, cap of a different value, and do it efficiently, charge is >> not conserved." >> >> Note the NOT CONSERVED. >> >> Now you say, "...the C*V (charge) on the first cap obviously becomes a >> different C*V on the second one". >> >> Where did the charge come from/go to? >> >> John "The Bloviator" Larkin is totally incapable of admitting error. >> >> I truly suspect you're too ignorant to understand :-( >> > >I'm glad my post got what it was suppose to get out. I kinda feel like >Breitbart. > Initial condition: C1 2F, 1 volt, 1 joule, 2 coulombs C2 1F, 0 volts, 0 joules, 0 coulombs Now remove all the energy from C1 and deliver it to C2. An inductor will move the energy nicely. Now C1 has 0 volts, 0 joules, 0 coulombs C2 has 1.414 volts, 1 joule, 1.414 coulombs. John
From: krw on 21 Jul 2010 19:07 On Wed, 21 Jul 2010 14:10:57 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: ><keithw86(a)gmail.com> wrote in message news:ed6b7de0-5287-47e4-9d4b-217880b3c2e5(a)5g2000yqz.googlegroups.com... >> Ok, give us a mathematical model of "divide by zero". > >Since we're taking the limit of two variables (R --> 0 and L --> 0), this is a multivariate calculus problem, and therefore it matters which variables we take to zero first, or in what proportion. > >It is only necessary to find two different answers to prove the limit does not exist, so we shall take simple directions (R and L axes, respectively). > >1. IFF the limits are equal, then the limit exists. >2. In the L = 0 case, half the energy disappears (E = 1/2 Eo); in the R = 0 case, the energy remains (E = Eo). >3. Because the answer is not equal under different conditions, the limit is undefined. QED. Which is why I didn't say "model R => 0".
From: krw on 21 Jul 2010 19:09 On Wed, 21 Jul 2010 16:16:49 -0500, "George Jefferson" <phreon111(a)gmail.com> wrote: > > ><keithw86(a)gmail.com> wrote in message >news:ed6b7de0-5287-47e4-9d4b-217880b3c2e5(a)5g2000yqz.googlegroups.com... >> On Jul 21, 12:59 pm, "George Jefferson" <phreon...(a)gmail.com> wrote: >>> "Tim Williams" <tmoran...(a)charter.net> wrote in message >>> >>> news:azG1o.20990$lS1.2654(a)newsfe12.iad... >>> >>> > "Michael F�rtsch" <michael.foert...(a)chello.at> wrote in message >>> >news:57c17$4c46f981$5472c223$14009(a)news.chello.at... >>> >> The total electrical energy after the charge has been transfered is >>> >> 50% >>> >> of the electrical energy that was stored in C1. The residual 50% had >>> >> been handed to the government as a charge transfer tax. >>> >>> > Wrong -- the inductance and resistance of the circuit is unspecified, >>> > so >>> > 1., there is no correct answer, and 2. it's a nonphysical circuit, so >>> > not >>> > only is it unspecified, it's meaningless. >>> >>> WRONG. That has nothing to do with it. We can "specify" that the >>> inductance >>> and resistance is 0. Just because this is physically not possible does >>> not >>> mean we cannot create such a hypothetical mathematical model. >> >> Ok, give us a mathematical model of "divide by zero". > >1/0? Nope. Tautology is not a mathematical model. >I don't see what this has to do with the problem though... I'm sure you >do... of course this assumes you are right. Model infinite current and zero time. The equations blow up (Larkin's "singularity").
From: Martin Riddle on 21 Jul 2010 19:54
"Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote in message news:rcie465itdu34iaajm1itdqslepu2i87r6(a)4ax.com... > On Wed, 21 Jul 2010 12:14:04 -0700, John Larkin > <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Wed, 21 Jul 2010 12:17:41 -0500, "George Jefferson" >><phreon111(a)gmail.com> wrote: >> >>> >>> >>>"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >>>message >>>news:dj7e465sga7fe3nq7hfl3f0uk601pvrem8(a)4ax.com... >>>> On Wed, 21 Jul 2010 11:19:31 -0500, "George Jefferson" >>>> <phreon111(a)gmail.com> wrote: >>>> >>>>> >>>>> >>>>>"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >>>>>message >>>>>news:s43e46la1p1vt11527eg3ptl9ulm44dfrj(a)4ax.com... >>>>>> On Wed, 21 Jul 2010 07:54:03 -0500, "George Jefferson" >>>>>> <phreon111(a)gmail.com> wrote: >>>>>> >>>>>>>Suppose you have two capacitors connected as >>>>>>> >>>>>>>--*-- >>>>>>>| | >>>>>>>C1 C2 >>>>>>>| | >>>>>>>----- >>>>>>> >>>>>>>where * is a switch. >>>>>>> >>>>>>>What is the total energy before and after the switch is closed(in >>>>>>>general). >>>>>> >>>>>> Energy is conserved, so it's the same, if you account for all the >>>>>> manifestations of energy. >>>>>> >>>>> >>>>>You didn't answer the question. I assume this because you don't >>>>>know. >>>>> >>>> >>>> State the question unambiguously and I will. >>>> >>>> As I said, the puzzle is both ancient and trivial, so probably JT >>>> invented it. There are web sites and even academic papers devoted >>>> to >>>> it. Given all that, how could I not understand it? >>>> >>> >>>Um you don't get it. Your ignorance in basic electronics amazes me. >> >>That's funny. But people can choose to be amazed in all sorts of ways. >> >> >> Michael >>>got it(although he didn't explain where the energy went but I think >>>gets >>>it). >>> >>>Assume the second cap is initially "uncharged" and has the same >>>capacitance >>>as the first. >>> >>>Then the initial energy is >>> >>>Wi = 1/2*C*V^2 >>>Wf = 2*1/2*C*(V/2)^2 = 1/4*C*V^2 = 1/2*Wi >>> >>>Hence the final energy of the system 1/2 what we started with. >> >>Miraculous calculation. Yours and about 300 web sites that admire this >>puzzle. >> >>You didn't wxplain where the energy went - see those 300 web sites - >>but you are assuming losses. Another solution is that no energy is >>lost, and it rings forever, in which case the final state that you >>cite never happens. The exact waveforms are actually interesting. >> >>> >>>I'd really like to hear your explanation but I know thats >>>impossible(as >>>you'll steal someone elses). After all your the one that believes >>>charge >>>isn't conserved... heres your change to *prove* it. >>> >>> >>> >> >>Check my previous posts. I noted the exact waveform across a resistive >>switch, for any values of C1 and C2, and an independent way to compute >>the energy lost in that switch. >> >>Given an inductor, one can move all the energy from one charged cap to >>another, uncharged one. If the C values are unequal, the C*V (charge) >>on the first cap obviously becomes a different C*V on the second one. >>I noted that here some weeks ago, too. >> >>This is all EE101 stuff. >> >>John > > Let the hedging begin... > > In Message-ID: <3b893612tjjndo8o4v1evro050nonjgp41(a)4ax.com> > > You said: > > "Right. If you dump all the energy from one charged cap into another, > discharged, cap of a different value, and do it efficiently, charge is > not conserved." > > Note the NOT CONSERVED. > > Now you say, "...the C*V (charge) on the first cap obviously becomes a > different C*V on the second one". > > Where did the charge come from/go to? > > John "The Bloviator" Larkin is totally incapable of admitting error. > > I truly suspect you're too ignorant to understand :-( > > ...Jim Thompson So, is this like "Wait 30 days and get a different answer?" , I play this all the time with those management types. Cheers |