Win Hill: Inverse Marx Generator ??

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>>>> >>> [snip] >>>>If you conserve energy, then you must have >>>> >>>>C1*V1^2 = C2*V2^2 >>> >>>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. >>> >>>John >>> >>> >> >>Would you care to prove that for us John? Mathematically, that is. No >>hand-waving. After all you do claim trivial EE101 :-) >> >> ...Jim Thompson > >Newbies will take note that Larkin has NOT responded to this request. > >Would someone out there like to mathematically prove that charge is >NOT conserved in Larkin's folly (and yet energy is ?:-) >

How about you, Win Hill? What do you think? ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Jim Thompson
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Sorry Jim, I don't think you are right this time. At almost all times caps have zero 'net' charge on them. There's just charge separation. Charge conservation is just not that important.

You can transfer the electric field energy to magnetic field energy and then back again.

George H.

Reply to
George Herold

Oooh. Its the old "where did the energy go" two cap puzzle.

This ought to be fun to watch.

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Paul Hovnanian     mailto:Paul@Hovnanian.com
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Paul Hovnanian P.E.

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Naaaah! It won't amount to anything. Win will go hide, rather then stand up on his haunches and declare Larkin wrong.

And all the newbies will lose :-( ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Jim Thompson
[snip]
[snip]

Which is trivial to solve :-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

The excess energy goes into the "KA-POW" you hear when you try the experiment with two 75V 10,000uF caps. :)

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Bitrex
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Reply to
amdx

Larkin fails to realize that V1 = V2.

V1*Q1 = V2*Q2

=> Q2 = V1/V2*Q1, V1 = V2 so Q1 = Q2.

You would think with all his vast knowledge that would understand basic 101 electronics.

+----+ | | C1 C2 | | +----+

If you discharge C1 into C2 then the voltages across them will be equal after a given time. The total charge will still not have changed.

The total charge Q = Q1 + Q2. As electrons move from the cap of higher voltage to lower voltage we end up with Q = (Q1 -+ de) + (Q2 +- de) = Q.

Reply to
George Jefferson

That simple riddle is ancient, possibly even older than JT.

Obviously charge is conserved in this circuit, independent of what impedance is used to bridge the caps or of when you observe the system. I certainly wouldn't dispute that.

What I *did* say is conveniently right at the top of your post.

To celebrate the 21st century, I have composed a new riddle:

Start with a 4 farad cap charged to 0.5 volts. Q = 2 coulombs.

Carefully saw it in half, without discharging it, such as to have two caps, each 2 farads, each charged to 0.5 volts. The total charge of the two caps remains 2 coulombs, whether you connect them in parallel or consider them separately.

Now stack them in series. The result is a 1F cap charged to 1 volt. That has a charge of 1 coulomb. Where did the other coulomb go?

I think this is a better riddle.

John

Reply to
John Larkin

One should not confuse charge with energy.

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Reply to
tm

Exactly the point I've been making. Some EEs seem to think that charge is always conserved. Some physicists seem to think that energy is always conserved. They can't both be right.

I'll side with the physicists on this one.

John

Reply to
John Larkin

There is no physical laws of "conservation of ...". There are, however, artificially designed parameters such as "energy", "charge", "momentum", etc. Those parameters are *defined* in such way that their value is preserved through certain transformations of a physical system. The only purpose of this is simplification of math; so it is possible to balance the states of a system instead of solving differential equations.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

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Reply to
Vladimir Vassilevsky

It is.

It is. You're just not accounting for where part of it went.

Even the ones that believe in AGW? ;-)

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Paul Hovnanian  paul@hovnanian.com
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Paul Hovnanian P.E.

But it's convenient to balance the books by calculating the total energy in a system and assuming it's constant. That can short-cut all sorts of circuit and signal processing problems, avoiding the calculus you suggest. I know of no cases where the energy balance thing has been violated. It would make the front page of the New York Times if it ever were.

You can't, in general, bookkeep "charge" and assume it's conserved; sometimes it is, sometimes it's not.

I've read that some of the far-out extensions of the Standard Model, or of string theory, propose that COE can be derived from basic theory. Nobody has done it yet, so it's still an assumption.

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John

Reply to
John Larkin

OK, enlighten me.

Slap a 1-ohm resistor across the 1F/1v cap and discharge it. You'll get 1 ampere-second out of it eventually. We started with 2 coulombs. Where did the other coulomb go?

John

Reply to
John Larkin

It is pointless to talk about energy balance, because the notion of energy is DESIGNED to be balanced through certain transformations. So we can balance the books instead of solving the equations to our convenience.

We can only prove that such and such particular transformation preserves the qualities defined like so and so.

Let's get clear with ABC physics before venturing into complicated stuff.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

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Reply to
Vladimir Vassilevsky

John, 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_."

Simply prove your statement and we'll leave you alone. Side-step it and we'll permanently label you the hoaxer (and coward) that you really are.

Win Hill, recognized by others on this group as the ultimate authority, is invited to prove Larkin's supposition. Are you up to it, Win ?:-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Larkin is claiming CHARGE is not conserved. BOTH are conserved... it's just that some, like Larkin, are too ignorant to know where "it" went :-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Hey, I'm a simple circuit designer. I assume COE to simplify making conclusions about circuits and signals and systems. It's always worked so far.

John

Reply to
John Larkin

No, your not making sense. When you use the term "conserve" you are implying a net conservation. It makes no sense to say something isn't conserved when you are not talking about the net effect because it is obvious.

Obivous charge in the sense you are talking about is not conserved. Take a battery. Electrons flow out of it... hence there is no "conservation".

If you charge a cap up with a battery(analogous to your cap to cap) there is no "conservation" in your sense because the cap "stole" electrons from the battery.

Yet the net CHARGE is CONSERVED and always will be(except possibly at scales near the planck time).

Your confusing conservation with distribution. If you take any distribution of charge you can easily say that any part of it will not be conserved. To prove this you can just move a charge out of that part under consideration.

Again, if you want to use such an obtuse definition for conservation then you are right. Generally when we talk about conservation we are saying so in terms of a closed system else it is generally meaningless/useless.

You can then say nothing is conserved. Heat, charge, momentum, etc...

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Read the first sentence:

"In physics, a conservation law states that a particular measurable property of an ****isolated**** physical system does not change as the system evolves."

Of course it requires a bit of intelligence to know what an isolated system is and how to use it in practice to get any meaningful result.

Now I suppose your argument will be that "conserved" has no relation to a conservation law?

Reply to
George Jefferson

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