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Author Topic: MH's ideal coil and voltage question  (Read 487938 times)

MileHigh

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Re: MH's ideal coil and voltage question
« Reply #720 on: May 29, 2016, 05:38:08 PM »
I don't know why this is being discussed again because I already discussed it with Magluvin on the other thread.  If you can imagine a cap transfer where no energy is lost and the two caps are at 7.071 volts then you need more charge than is in the original cap sitting at 10 volts.  An idealized arrangement with a coil and a switch can do this.  Without the idealized arrangement the initial amount of charge in the original cap loses some energy through resistance when it spreads itself out between the two caps.

Conservation of charge equals conservation of momentum in the two colliding masses example.

minnie

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Re: MH's ideal coil and voltage question
« Reply #721 on: May 29, 2016, 06:21:15 PM »



  What you'll have to do is brush-up on yer polynomial integrals !

minnie

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Re: MH's ideal coil and voltage question
« Reply #722 on: May 29, 2016, 09:45:19 PM »



 Energy stored on a capacitor has counterintuitive elements.

minnie

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Re: MH's ideal coil and voltage question
« Reply #723 on: May 30, 2016, 12:02:31 AM »



  Trust the experts, constant current rules!!!
       John.

verpies

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Re: MH's ideal coil and voltage question
« Reply #724 on: May 30, 2016, 12:34:20 AM »
Why would that be John?
I think he wrote that, because two electrons can represent different energies depending on their separation distance and the work needed to move them closer together is a result of their repulsion force integrated over the distance of their approach. 
Reminder: The instantaneous repulsion force of two electrons is inversely proportional to the square of the distance (1/d2) between them.

BTW: this is an example how the same amount of charge (here, the two electrons) can represent very different levels of energy.
In other words: Charge alone, is not energy.

MileHigh

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Re: MH's ideal coil and voltage question
« Reply #725 on: May 30, 2016, 01:00:10 AM »
When people start going into stuff like charge carriers and whatnot, it's usually a sign that the discussion is going nowhere and people are just spinning their wheels and going through the same old motions.

Nobody was able to answer the first question, and that includes all you experimenters.

How about trying to tackle Partzman's question now that the first question has been answered for you?

It went something like this:  You have an ideal five henry inductor.  There is an ideal voltage source that is put across the inductor at t=0 and for two seconds the voltage applied across the inductor is a linear ramp that starts at zero volts and ends at two volts.  After that the voltage is zero volts.  What happens?

Now, is anybody going to say something about this?

tinman

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Re: MH's ideal coil and voltage question
« Reply #726 on: May 30, 2016, 01:05:03 AM »


   Capacitor = potential .
 
   Sounds good to me.

Quote
Inductor = kinetic.

With the exception of MHs question,between T=3s and T=5s,where the magnetic field is stable,and so the stored energy is potential energy.


Brad

tinman

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Re: MH's ideal coil and voltage question
« Reply #727 on: May 30, 2016, 01:21:40 AM »
When people start going into stuff like charge carriers and whatnot, it's usually a sign that the discussion is going nowhere and people are just spinning their wheels and going through the same old motions.

Nobody was able to answer the first question, and that includes all you experimenters.

How about trying to tackle Partzman's question now that the first question has been answered for you?



Now, is anybody going to say something about this?

Quote
It went something like this:  You have an ideal five henry inductor.  There is an ideal voltage source that is put across the inductor at t=0 and for two seconds the voltage applied across the inductor is a linear ramp that starts at zero volts and ends at two volts.  After that the voltage is zero volts.  What happens?

The current ramps up on a linear ramp,but 90* behind that of the voltage ramp,and ends with a value of 800mA,and maintains that value until interrupted.?


Brad

MileHigh

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Re: MH's ideal coil and voltage question
« Reply #728 on: May 30, 2016, 01:30:12 AM »
That's not right but more importantly how did you arrive at that answer?  That's the whole point for the brainstorming, to bounce ideas back and forth.

The other question is why are you talking about phase here and how do you define it?

Magluvin

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Re: MH's ideal coil and voltage question
« Reply #729 on: May 30, 2016, 01:33:57 AM »
Question Mags,,

Are these electrons stacked up in a straight line or across in a straight line?

It takes more "energy" to put the last electron into place than it does the first one,, just like stacking bricks,, the low ones are easy,, the high ones are harder.

Hmm. How much simpler can I put it?  Poynt is stumped also.


Ok. Here is another set of questions. We will start from the very beginning. These should be very basic knowledge questions.  All refer to a 1000uf cap charged from 0v to 10v....


Does anyone here believe that when we charge a cap, that we are depleting the pos plate of electrons, and adding extra electrons to the neg plate?

If we have say a 1000uf cap and we charge it from 0v to 10v, are there electrons pulled from the positive plate and electrons pumped into the negative plate during the charge period?

Is the reason the positive plate becomes positively charged because it is stripped of electrons, and that the negative plate is becomes negatively charged is because it has taken on extra electrons?


If you do not agree that the answer to those 2 questions should be 'Yes', then I need an explanation as to why.


Mags

poynt99

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Re: MH's ideal coil and voltage question
« Reply #730 on: May 30, 2016, 02:41:05 AM »
I agree.

poynt99

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Re: MH's ideal coil and voltage question
« Reply #731 on: May 30, 2016, 03:10:50 AM »
"Haven't you done your own test with this? What was your result?"

My results were that I get 5v per cap after cap to cap transfer. ??? And What Im saying is that I think that even if they were ideal caps, 10v cap to 0v cap, that we would still have 5v per cap.
Well we can't have ideal conductors (when shorting an ideal cap or voltage source), so this scenario is unachievable/unsolvable to begin with. You would have infinite current as soon as the two caps are connected.

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Here is a couple of questions for you....


We have 2 'Ideal' capacitors of the same value. One is charged at 10v and the other at 0v. 

Lets say just for simplifying the example that the 10v cap has an imbalance of 2000 electrons (pos plate -1000 and neg plate +1000) between the pos and neg plates and the 0v cap has no imbalance.

So we do the cap to cap zap. When all is said and done, we disconnect the caps. What would the voltage be across those caps? And what would the electron imbalance count be for each cap?
Assuming the universe didn't blow up trying to source infinite current, the voltage would be 7.07V in each cap. The electron balance would be 707 on each plate, vs 1000 when it was 10V, assuming there is a valid linear relationship between the charge count and voltage of course.

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Now we will do the same with real world caps..... Same values as described above.....

Cap to cap zap and disconnect. What will the voltages be across those caps? And what would the electron imbalance count be in this example?
Surely you know the answers? 5V and 500 electrons.

Magluvin

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Re: MH's ideal coil and voltage question
« Reply #732 on: May 30, 2016, 03:19:34 AM »
I agree.

Ok.

When I was saying to simplify things by saying that the electron count was -1000 electrons for the Pos plate and +1000 electrons for the Neg plate when the cap is charged to 10v, the 1000 number is just to simplify things.  The real numbers are probably so large, but the symmetry should be fairly close. Nearly as many electrons come out of the Pos cap lead as there is going in to the Neg cap lead.

Would you agree that if we charged the cap from 0v to 10v, and we 'could' count the numbers of the electron count offset between the Pos and Neg plates, then if we discharged the cap to 0v and recharged the cap to 10v, and we did another count of the electron offset between the two plates, would that number be the same as the offset count after the first charge?    Im talking theoretically 0v and 10.00000000000000000000000000000000000v Not a 10.001v or 9.999999v.  0v to 10v.


Mags


poynt99

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Re: MH's ideal coil and voltage question
« Reply #733 on: May 30, 2016, 03:22:27 AM »
Agreed. I think you may want to skip ahead; see my last response to your questions.

Magluvin

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Re: MH's ideal coil and voltage question
« Reply #734 on: May 30, 2016, 04:28:28 AM »
Agreed. I think you may want to skip ahead; see my last response to your questions.

"Well we can't have ideal conductors (when shorting an ideal cap or voltage source), so this scenario is unachievable/unsolvable to begin with. You would have infinite current as soon as the two caps are connected."


"Assuming the universe didn't blow up trying to source infinite current, the voltage would be 7.07V in each cap. The electron balance would be 707 on each plate, vs 1000 when it was 10V, assuming there is a valid linear relationship between the charge count and voltage of course."

Ok. Good.   

1 cap at 10v -  +1000 excess electrons on the Neg plate and -1000 electrons on the Pos plate.

1 cap at 0v -   each plate has an equal amount of electrons and no imbalance.

 If we let the cap discharge into a 0v cap and equalize, how do we get +707 offset count on both caps Neg plates and -707 on both caps Pos plates?  If we divide 1000 by 2 we get 500 + and - for each cap.  Where did we get the extra electrons to get the 207 count difference?   Its like saying if we have 1 gal of water and we divide it equally between 2 containers that each container would have .707 gal of water at no loss, but if we ended up with .5 gal per container that we have lost half. In a way.
 The total offset for the 2 ideal caps would be 1414 electron offset count.  We started with 1000 offset in the source cap. Can you see the discrepancy? ;)

So how do we account for the extra electrons in the ideal cap to cap?  I can see how we do it with the inductor, where we cut off the source cap at 7.07v, then let the inductor freewheel electrons from the Pos of the receiving cap to the Neg until it reaches 7.07v.  All say done with super fast timed switching, no diodes..

But with the cap to cap, there isnt the option of gaining extra electrons in the offset to alter the original count. They can only be distributed equally between he 2 caps. 1000 + and - offset count of the source cap to 1000+ and - offset count for both caps total, 500 + and - offset each.   The above explanation with the inductor, we stopped the flow from the source cap at 707 + and - offset count, and at that time the inductor pumps the receiving cap the rest of the way by way of taking from the Pos and giving to the neg.

Similar to the air tank with an air motor with fly wheel.  100lb air on source tank and 0lb in the receiving tank. Open the valve and the pressure gets the flywheel going while the receiving tank fills.  We cut of the source tank at 70.7lb and switch over to letting the flywheel pump 'extra' air from the outside, till the receiving tank is at 70.7lb.  If we simply did tank to tank, we would have 50 lb per. Heat losses or not, tank to tank could never be a result of 70.7lb per tank all said and done.


So if we can agree on the simple mathematics of the offset count, then we would have to agree that the ideal cap to cap would result in 5v per cap. So where did we lose the 50%energy with no resistance and or heat losses?   Thats my point Poynt. ;D

Mags