Charge Conservation - Hint of the Day
in [Design]
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From: John Larkin on 20 Jul 2010 21:48 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
From: Jim Thompson on 20 Jul 2010 22:15 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 ;-) ...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 |
From: kevin93 on 20 Jul 2010 23:23 On Jul 20, 6:48 pm, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Tue, 20 Jul 2010 19:36:22 -0500, John Fields > > > > > > <jfie...(a)austininstruments.com> wrote: > >On Tue, 20 Jul 2010 08:24:26 -0700, 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, 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 I presume you meant 1 second time constant with 1 milliohm in parallel. kevin
From: Bill Bowden on 20 Jul 2010 23:33 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. -Bill > ...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 athttp://www.analog-innovations.com| 1962 | > > I love to cook with wine. Sometimes I even put it in the food.
From: John Larkin on 20 Jul 2010 23:41
On Tue, 20 Jul 2010 20:23:44 -0700 (PDT), kevin93 <kevin(a)whitedigs.com> wrote: >On Jul 20, 6:48�pm, John Larkin ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> On Tue, 20 Jul 2010 19:36:22 -0500, John Fields >> >> >> >> >> >> <jfie...(a)austininstruments.com> wrote: >> >On Tue, 20 Jul 2010 08:24:26 -0700, 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, 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 > >I presume you meant 1 second time constant with 1 milliohm in >parallel. Right. That would give the 1 coulomb. John |