Charge Conservation - Hint of the Day
in [Design]
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From: Jim Thompson on 25 Jul 2010 12:45 On Sun, 25 Jul 2010 01:30:08 -0700, Robert Baer <robertbaer(a)localnet.com> wrote: >Richard Henry 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? >> >> I was expecting an actual answer to this in the recently-revealed >> paper. I guess I was misled. > You want an answer already? > Go to Radio Shack and make them perform to their ad (and if they >don't, sue). Richard Henry proves my point that the "youngsters" here (can't use "young bucks" anymore, John "The Bloviator" Larkin gets sexually aroused :) don't know any fundamentals and can't think for themselves. All they want is "actual answer(s) �" :-( Another "hint": Charge is the time-integral of current. Not that I think that will help. It's been said multiple times in the thread, though certain obfuscators simply say, "ampere-seconds", to keep it unclear, and make it better fit their loose and hare-brained explanations. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Cranky Old Git With Engineering Mind Faster Than a Speeding Prissy
From: Richard Henry on 25 Jul 2010 13:38 On Jul 25, 9:45 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On-My- Web-Site.com> wrote: > On Sun, 25 Jul 2010 01:30:08 -0700, Robert Baer > > <robertb...(a)localnet.com> wrote: > >Richard Henry 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? > > >> I was expecting an actual answer to this in the recently-revealed > >> paper. I guess I was misled. > > You want an answer already? > > Go to Radio Shack and make them perform to their ad (and if they > >don't, sue). > > Richard Henry proves my point that the "youngsters" here (can't use > "young bucks" anymore, John "The Bloviator" Larkin gets sexually > aroused :) don't know any fundamentals and can't think for themselves. > > All they want is "actual answer(s) ®" :-( > > Another "hint": Charge is the time-integral of current. > > Not that I think that will help. It's been said multiple times in the > thread, though certain obfuscators simply say, "ampere-seconds", to > keep it unclear, and make it better fit their loose and hare-brained > explanations. > I didn't really expect an answer, especially after reading your "duh!"- level bowl of porridge.
From: markp on 7 Aug 2010 11:12 "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? > > ...Jim Thompson > -- A somewhat non-sensical question, designed I suspect to illicit responses that try to answer if definitively so Jim can lambast them for their ignorance. But I'm going to attempt to give an answer, with some assumptions: An inductor cannot store net charge. The same current flows in as flows out (as for a capacitor in a circuit, which also cannot sore net charge, for the same reason). Assuming the 1A is steady state there is no voltage across the inductor. We can say the inductor has stored energy, given by (L * I^2)/2. As an example, we could connect a capacitor across it in parallel, as the voltage across the capacitor rises the current through the circuit falls, until we reach a state where no current is flowing. Assuming no resistive losses, the energy that was in the inductor would then be in the capacitor. A few definitions: Iinit is the initial current flowing through the circuit, in this case 1A. Q is the absolute value of the charge present on the plates of the capacitor at the time the current reduced to zero (+Q on one plate, -Q on the other). This means at the point of zero current, (L * Iinit^2)/2 = Q^2/(2 * C), or Q = sqr(C * Init^2 * L) = Iinit * sqr(L*C). So, the total charge (i.e. the time integral of the current) that flowed around that circuit until the current drops to zero is actually proportional to the square root of the capacitance we placed across the inductor. The inductor has essentially pumped charge around the circuit by voltage given by -L* dI/dt. Note that same amount of charge has come back into the inductor via the circuit. This is a parallel resonant circuit, the frequency of which is 1/(2 * pi * sqr(L*C)), and will continue to oscillate forever if there are no energy losses. So, the inductor cannot 'deliver charge' as such, but it can transfer its stored energy by pumping charge around the complete circuit in the same way a water pump pumps water. The total amount of charge it can pump until the current reaches zero is dependent on what is connected to it. Technically you can place a piece of wire across the inductor and, assuming no resistive losses, the current would continue to flow forever. Mark.
From: Phil Hobbs on 7 Aug 2010 15:22 On 8/7/2010 11:12 AM, markp wrote: > "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? >> >> ...Jim Thompson >> -- > > A somewhat non-sensical question, designed I suspect to illicit responses Malapropism of the day, but a beautiful summation. > that try to answer if definitively .... Try doing the math, folks. It isn't hard, even if it isn't as much fun as slagging each other off in public, and you learn a lot more per hour. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 email: hobbs at electrooptical dot net http://electrooptical.net
From: markp on 7 Aug 2010 16:11
"Phil Hobbs" <pcdhSpamMeSenseless(a)electrooptical.net> wrote in message news:C8KdnZnxbYJyLMDRnZ2dnUVZ_v6dnZ2d(a)supernews.com... > On 8/7/2010 11:12 AM, markp wrote: >> "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? >>> >>> ...Jim Thompson >>> -- >> >> A somewhat non-sensical question, designed I suspect to illicit responses > > Malapropism of the day, but a beautiful summation. Er, yipe. Solicit!! :-) > >> that try to answer if definitively .... > > Try doing the math, folks. It isn't hard, even if it isn't as much fun as > slagging each other off in public, and you learn a lot more per hour. > > Cheers > > Phil Hobbs > |