Charge Conservation - Hint of the Day
in [Design]
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From: John Larkin on 20 Jul 2010 23:47 On Tue, 20 Jul 2010 20:33:41 -0700 (PDT), Bill Bowden <wrongaddress(a)att.net> wrote: >On Jul 20, 8:24�am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On-My- >Web-Site.com> wrote: >> Charge Conservation - Hint of the Day: >> >> How many Coulombs can a 1mH inductor charged to 1A deliver? >> > >Well, from a novice point of view, 1 amp is the same as 1 coulomb per >second, so I would imagine any inductor charged to 1 amp can deliver 1 >coulomb per second indefinitely into a shorted circuit of zero ohms. >Why would it ever be different? > >I think there are some super conducting resonate circuits (LC tank >circuits) that were initially charged with some energy and continue to >oscillate for several years. The coulombs just go back and forth >between the inductor and capacitor. > The problem is mostly the Q of the capacitor. Real-life Qs in the millions are possible with superconductive coils and cold teflon caps. www.lnl.infn.it/~auriga/auriga/papers_src/varfreq.pdf Of course, you don't get many net coulombs from an AC current! Superconductive magnets circulate hundreds of amps through their shorting switches for years. They might lose a couple of PPM current per day. John
From: Tim Wescott on 21 Jul 2010 00:10 On 07/20/2010 07:15 PM, Jim Thompson wrote: > On Tue, 20 Jul 2010 18:48:21 -0700, John Larkin > <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Tue, 20 Jul 2010 19:36:22 -0500, John Fields >> <jfields(a)austininstruments.com> wrote: >> >>> On Tue, 20 Jul 2010 08:24:26 -0700, Jim Thompson >>> <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >>> >>>> Charge Conservation - Hint of the Day: >>>> >>>> How many Coulombs can a 1mH inductor charged to 1A deliver? >>> >>> --- >>> Well, let's see... >>> >>> Since the collapsing magnetic field around an ideal one henry inductor >>> with one ampere of current in it will deliver about 6.24e18 electrons >>> into any load when its current source is abruptly terminated, a one >>> millihenry coil, under the same conditions, should deliver about about >>> three orders of magnitude less, about one millicoulomb. >>> >>> JF >> >> Connect the 1 mH inductor to a 1 milliohm resistor. It will initially >> deliver 1 amp, decaying with a 1 millisecond time constant. Wait long >> enough and you'll see 1 coulomb pass through the resistor. >> >> Repeat with a 1 uohm resistor. Tau is 1000 seconds, Q=1000 coulombs. >> >> John >> > > Sonnova gun, who would have thunked it ?:-) > > Sweat, John, sweat, the day of reckoning has arrived... your BS must > stop... and it will ;-) Since you were the one who brought political parties into the discussion -- I can see that you're a Dubya Republican, not a Regan Republican. Keep shouting, eventually anyone who wants civil discourse will get disgusted with responding. Then you can sit in your little room and tell yourself you've won. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
From: John Devereux on 21 Jul 2010 02:59 John Fields <jfields(a)austininstruments.com> writes: > On Tue, 20 Jul 2010 08:24:26 -0700, Jim Thompson > <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: > >>Charge Conservation - Hint of the Day: >> >>How many Coulombs can a 1mH inductor charged to 1A deliver? > > --- > Well, let's see... > > Since the collapsing magnetic field around an ideal one henry inductor > with one ampere of current in it will deliver about 6.24e18 electrons > into any load when its current source is abruptly terminated, No, that's is the initial *rate* at which it will "deliver" charge, i.e. 1 amp equals ~6.24e18 electrons *per second*. Unfortunately Jim is being purposefully vague with the critical points and refuses to define his terms. Then, when someone uses a definition different from his private one, he will turn around and "prove them wrong". Two weeks later, by appointment only. For example, how are we supposed to interpret "deliver"? A certain amount of charge will flow *through* the load, completing a circuit back to the other end of the inductor. But has it been "delivered"? In any normal electronic engineering context we would say so, but here? It all returned to the source, so maybe not. You can sensibly *define* it either way. > a one millihenry coil, under the same conditions, should deliver about > about three orders of magnitude less, about one millicoulomb. > > JF -- John Devereux
From: Robert Baer on 21 Jul 2010 04:18 Jim Thompson wrote: > On Tue, 20 Jul 2010 08:58:13 -0700, John Larkin > <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Tue, 20 Jul 2010 08:53:22 -0700, Tim Wescott <tim(a)seemywebsite.com> >> wrote: >> >>> On 07/20/2010 08:24 AM, Jim Thompson wrote: >>>> Charge Conservation - Hint of the Day: >>>> >>>> How many Coulombs can a 1mH inductor charged to 1A deliver? >>> That's insufficient information, and I rather expect that you know it. >> He promised us, a couple of weeks ago, a "mathematical proof" of >> something or other charge related. Is this lame snarky "hint" the best >> he's been able to come up with? >> >> John > > Cluck! Cluck! Cluck! Cluck! ESAD! > > I may be a snarky ol' git, but I'm GOOD ;-) > > I'm a graphical/pictorial sort of guy... > > Normally I'd do this sort of thing on a white board, before an > audience at one of my seminars, only an outline in front of me, then > "play" the audience. > > So I've been struggling to create the pictorial on a series of sheets > of paper to properly describe (and solve the issue). > > It's funny, the only time I've had time to think this through has been > while sitting in doctors' waiting rooms. This morning, at > Barnet-Dulaney (wife's eyes, YAG lasers, cataracts), I fitted the > pictorial together in my head. > > Within the next 48 hours you, John "The Bloviator" Larkin (and ALL > your supplicants) are going to be BURNED AT THE STAKE... > > One-by-one every one of your STUPID STUPID STUPID statements will be > refuted (message ID's supplied to prove you made the STUPID STUPID > STUPID statements). > > I'm working now on how to distribute the material so that it can't be > disseminated, so that everyone can have a good laugh... BEHIND YOUR > WORTHLESS BACK ;-) > > RECANT! RECANT! THE END IS NEAR :-) > > ...Jim Thompson Allow me to enter the game with a STUPID question: what does an *inductor* have to do with a *charge*?
From: George Jefferson on 21 Jul 2010 08:51
"Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote in message news:jqfb469iggbg6dkeu84c8kgp3m9g0alr3m(a)4ax.com... > Charge Conservation - Hint of the Day: > > How many Coulombs can a 1mH inductor charged to 1A deliver? > > Charged to 1A? hahaha, are you serious? Do you mean 1A flowing through it after steady state has been reached? |