Charge Conservation - Hint of the Day

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

I presume you meant 1 second time constant with 1 milliohm in parallel.

kevin

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

=A0 =A0 ...Jim Thompson

=A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 | =A0 =A0 et =A0 =A0 =A0|

=A0|

=A0 =A0 =A0 |

Right. That would give the 1 coulomb.

John

The problem is mostly the Q of the capacitor. Real-life Qs in the millions are possible with superconductive coils and cold teflon caps.

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

"No. It's provided to cause young bucks to do some thinking. Looks like it didn't work with you :-("

OK. Tell me how I'm supposed to take the "Looks like it didn't work with you". To me it sure looks like you're unthinkingly accusing me of not thinking.

No Jim, I think it's that "discussion" is only allowed if you kiss up to Jim, 100%. Or maybe 118%:

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.

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.

Allow me to enter the game with a STUPID question: what does an

On a sunny day (Tue, 20 Jul 2010 18:14:16 -0700) it happened Jim Thompson wrote in :

Already arrogant at young age...

My first thought was 'You need a shrink'. Then thinking a bit more, I came up with the insight that even if you *were* right it would be very hard to agree with you because of your arrogance. But then there is nothing to agree or disagree with in all this you say, as you only ask questions, and fail at the answers. John gave a beautiful reply how the coil would discharge into a low value R similar to a capacitor. The 'art' of only asking questions is IIRC called 'Philosophy', many of those have come, many have gone, nothing they ever did helped anyone, except get people more confused. That is why philosophy is not for me. In fact I think philosophers are in eternal 'hell' as they sort of are in a brain loop. So you made your own. Snap out of it :-) If there is life then there is hope. Is that so? Oh shit, philosophy!

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Charged to 1A? hahaha, are you serious? Do you mean 1A flowing through it after steady state has been reached?

Of course if you connect a "charged" inductor to a resistor, literal charges - electrons - will enter one end of the resistor and exit the other. The resistor is not electrostatically charged by that flow, but some number of ampere-seconds does flow through the resistor, and ampere-seconds are coulombs. The resistor converts the charge flow to heat.

If a current source is connected to a capacitor, we circuit designers say that charge is put *into* the capacitor, in the sense that some number of ampere-seconds - coulombs - flow through the cap. Unlike the resistor, those coulombs change the internal state of the cap in a way that allows us to disconnect the cap, wait a while, and then use the "charged" cap as a source to make current. It sure looks like we poked coulombs *into* (not just onto, in the electrostatic sense) the capacitor, and we can extract them later, and the numbers balance precisely. So we EEs talk as if charge is stored in capacitors and batteries. Physics purists may quibble, but it works.

John

Steady-state doesn't matter but sure, why not? It's common to talk about charging an inductor, namely connecting a voltage to it and allowing it to integrate up a current.

Those are just shorthand words that EEs use; so quibble all you want. What matters is that we get the numbers right. Go turn on your television or start your car. Do they work?

John

His version of fun lately seems to have a lot to do with "young bucks", and I don't think he is fantasizing about adolescent male deer.

John

Hi Tim, I agree with your calculation. But not the interpretation. Sure you integrate current over time and you get charge. But this is not the charge delivered to a resistor, it is how much charge flowed through it. (Oh unless that's what is meant by delivered.)

George H.

Cluck! Cluck! Cluck! ...Jim Thompson

It is not me that's the BU pimp ;-) ...Jim Thompson

That's a common way of stating it. When we put parts on boards, their electrostatic potential is not often of concern. So we say that we put charge into a capacitor or a battery, literally we say "charge a battery" or "charge a capacitor" as opposed to "run charge through a capacitor", and we measure how much in ampere-seconds, namely coulombs.

Since both a cap and a battery save the ampere-seconds and can return/deliver them later, it's reasonable to think that they stored charge.

The numbers work. Engineering is about what works.

John

Engineering is about what works _all_the_time_, under _all_environmental_conditions_.

Schlocky is for Larkin's. ...Jim Thompson

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