MH's ideal coil and voltage question

[tinman]

In an attempt to enlighten the non-believers (those having difficulty understanding currents through voltage sources), let's alter/simplify MH's question to the following:

- same ideal voltage source and ideal 5H inductor connected across each other.
- between t=0 and t=3, V=+4V
- between t=3 and t=6, V=-4V
- from t=6 to infinity, V=0V
(see scope shot)

We know from previous discussions that between t=0 and t=3, the circuit current will ramp up linearly to 2.39A. I think everyone agrees with this, even the non-believers. We can also calculate the power and conclude that the power delivered by the voltage source ramps up from 0W to 9.56W during the same period of time. But since we know that the current and voltage in a voltage source are 180º out of phase, the power will actually ramp down to -9.56W.

What happens between t=3 and t=6 when the voltage inverts from +4V to -4V? Well, the non-believers have stated the following:
But how can that be? Real world experiments certainly don't result in the catastrophic end of the earth, and a simulation debunks this notion as well. Well, the non-believers argue that the L/R ratio of 5000:1 is not close enough to ideal (5H/1m), yet I have shown via sim that a ratio of even 100:1 is close enough for a 5% error. That converts to a total series resistance of 50m Ohms.

The fact is, most high quality high power audio amplifiers have an output damping factor of about 400:1, which means the output resistance is on the order of 20m Ohms (based on 8 Ohm load). So a big audio power amp is a good ideal voltage source.

The other fact is that we can indeed short out an ideal inductor that has current flowing through it, by ideal wire or ideal voltage source. If in our example the inductor is shorted by an ideal wire right at t=3, what happens? does the inductor and the world blow up? I think we all agree that the current would remain at 2.39A. If the voltage source went to 0V rather than -4V at t=3, we know that it would act the very same way as the previous case of the ideal wire, and the current would remain at 2.39A and there would be no explosions.


Green=voltage Source
Red= Circuit Current
Purple= Voltage Source Power

Even the best some times make mistakes.

Quote post 63-Poynt
My blown universe post was a bit of a ruse. In fact it implied the opposite of what would theoretically happen, that is, "nothing".

Quote post 74-me
So you are saying that at T=0--the instant the ideal voltage is placed across the ideal inductor,nothing would happen?--no voltage would appear across the ideal inductor?.

quote post 81-Poynt
Yes, nothing will happen with the ideal inductor, i.e. it will have 4V (or whatever the voltage is at any point in time) across it and zero current through it for ever and ever.

Quote post 84-MH
Brad:
You have actually been given part of the answer, and you see that you were dead wrong.  Turn that into a learning experience.
Seems at this time,both myself and Poynt are wrong.

Quote post 106-Poynt
Unless I'm overlooking something, or don't correctly understand the question, there will be no current, and the voltage across the inductor will be whatever the voltage source is at any one time, from t=0 to the end of time.
Given that tau=infinity, there can be no change in either I or V. Indeed if R is non-zero, there will be a current and the voltage change over time.

Quote post 123-Poynt
For your test (13s of a few different voltages), the different voltages have no affect on the outcome.

So the question could have been asked with one voltage and still have the same answer, correct?
I did the simulation with 0.0000000001f (femto) Ohms, which is very very small, and ran it for 100s, far exceeding the limit of your test. The current stayed flat at 0A for the full 100s. Needless to say the voltage across the coil also remained at 4V for the entire 100s.
I think we can conclude from these results that my answer is correct.
So here a very small value of resistance was used in the sim,and an answer given by the sim.
Odd that as soon as we increase the resistance of the coil,the sim starts showing different results.
Was the sim unable to replicate the actual question?.

Quote post 56-MH
The sim will work perfectly

What happens when the sim dose not show the results MH wants to see
Quote post 127-MH
Perhaps forget about the sim and do it in your head

Quote post 328-verpies
It is impossible to connect such voltage source across a shorted ideal inductor, because in such case  this voltage source would see a load, which does not have any resistance nor reactance

And this is the part you are all missing here.
We have agreed that between T=3s and T=5s,when the voltage value is 0v,a current of 2.4 amps will continue to flow through the ideal coil and ideal voltage source circuit,and will not fall in value,due to there being no resistance in this loop. This can only mean that the loop is a dead short,or shorted loop-continual loop with no resistance.So the ideal voltage source !is! the ideal short across the ideal coil,and this inductor has no resistance,and since the current flow is steady at 2.4 amp's,it also has no reactance. At T=5s,we are now going to try and place a negative voltage across this shorted ideal coil

Quote post 7--MH
no,a voltage cannot exist across an ideal inductor that has a DC current flowing through it.
Quote post 336-Poynt
All inductors, whether ideal or real will have a voltage across them when there is current through them, regardless if the current is changing or not.
Who is correct here?.

But my example switches the voltage from +4V to -4V, right at the instant 2.39A is flowing in the coil and voltage source. What happens next is the opposite from the period between t=0 and t=3; the current ramps down from 2.39A to 0A, and the power instantly changes from -9.56W to +9.56W, and ramps back down to 0W. The energy stored in the inductor is returned to the voltage source. No energy was dissipated when the inductor was energized, and none is dissipated when it de-energizes.

Quote post 425-MH
An ideal voltage source does not "contain energy"


It would seem that there needs to be a few things ironed out,as no correct answer can be obtained from those that are trying to give it,being in disagreements with each other.

First things first
MH-a voltage cannot exist across an ideal inductor that has a DC current flowing through it

Poynt-All inductors, whether ideal or real will have a voltage across them when there is current through them, regardless if the current is changing or not

Second
MH-An ideal voltage source does not "contain energy

Poynt-TThe energy stored in the inductor is returned to the voltage source


Brad

[picowatt]

And this is the part you are all missing here.
We have agreed that between T=3s and T=5s,when the voltage value is 0v,a current of 2.4 amps will continue to flow through the ideal coil and ideal voltage source circuit,and will not fall in value,due to there being no resistance in this loop. This can only mean that the loop is a dead short,or shorted loop-continual loop with no resistance.So the ideal voltage source !is! the ideal short across the ideal coil,and this inductor has no resistance,and since the current flow is steady at 2.4 amp's,it also has no reactance. At T=5s,we are now going to try and place a negative voltage across this shorted ideal coil

And when the applied voltage goes negative (changes), the inductor's reactance limits the change in current...

PW

[MileHigh]

Resonance and tuning both play a great part to the efficient running of an ICE both internally and externally.

Yes, it's easy to say those things.  But assuming that we are talking about the true scientific and engineering definition for resonance, so far the only thing that I am aware of is Helmholtz resonators for the air intake of a two-stroke engine.  For a modern four-stroke engine in a typical car, I am aware of nothing at all.

The word resonance is a ridiculously abused, misunderstood, and recklessly applied concept on the free energy forums.  In Russ' forum on the Rodin coil testing thread, someone posted this "resonance" clip called "Resonance in a bifilar coil."

https://www.youtube.com/watch?v=qtI1CPBSm-o

The clip has absolutely nothing whatsoever to do with resonance, nada.  However, presumably most of the readers of the thread are gobbling it up and believing it does.

If you can make valid points about resonance in an ICE, I would be most interested in learning about it.  But just throwing the term around like a marketing buzz word or some mechanic's shop talk will not work for me.

MileHigh

[MileHigh]

Even the best some times make mistakes.

The most cynical part of that posting is that Poynt got off to a shaky start at one point in the discussion and part of it was because he got thrown off by what his sim was saying.  His bad sim was reinforcing his mistaken preliminary thoughts.  Within one or two days clarity came back to him and he retracted his incorrect statements.  Everybody following the thread was witness to this.

And here you are like a clown repeating some of his incorrect statements that he already retracted as part of a setup for your posting where you show conflicting viewpoints being expressed by some people.

Do you understand how doing that is beyond ridiculous on your part?  It's just shameless unethical and incorrect behaviour.

Beyond that, what you should do is do a followup posting where you demonstrate all of your new knowledge and resolve all of the apparent conflicts and explain the rationale for each resolution.  Enough work has been put into this thread by many people.  A countless number of your misunderstandings, mistakes, or obstinate refusals to budge from wrong positions have been argued out in a sincere effort to bring this question to a successful conclusion.

So that's my suggestion to you:  Do a bit of shining and list the apparent conflicts and disagreements on the technical points one by one and and then resolve each one with the correct answer with a full explanation for each answer where you demonstrate competency in the subject matter.

MileHigh

[poynt99]

I know you can do much better than that Brad.

I put time and effort into that post, which clearly illustrates what happens. I'd be interested in your thoughts on that particular post and why you still believe the results shown are incorrect.

Even from a layman's point of view (and I'm not implying you are a layman), I would think the scope shot makes perfect sense.

For example, do you not agree that the calculated power from t=3 to t=6 ramps from +9.56W to 0W? We know there is 2.39A of current flowing, and now that the voltage has reversed, it is actually in-phase with the current, so the power goes positive, i.e. +2.39 x -(-4) = +9.56W.

Green=Voltage Source Voltage
Red=Circuit Current
Purple=Voltage Source Power