MH's ideal coil and voltage question

[MileHigh]

Thank you PW.

I am willing to lean,but i am not willing to let MH make me look like i have no idea as to what is going on here.
I would like to have good standing with those around me,but MH is doing his best to discredit that good standing,and i just cant sit back from that,and i dont believe you,Poynt,or anyone else would either.

Brad.

Fix this statement Brad to show you have an idea:

Yea--good one MH--only we do not have a loop,we have a coil attached to a voltage supply.

[picowatt]

The bottom line is that the the battery causes current to flow into the coil, and any talk about the CEMF causing current to flow into the battery, tangible or hypothetical, is wrong.  We are talking about a simple current loop here.

I do not recall Tinman suggesting that the CEMF was sufficient to actually reverse the flow of current and cause current to flow into the battery.  Perhaps I missed that.  Although a bit on the loose side where I pointed it out, his definition of CEMF was, for the most part, correct.

Brad can talk trash too, so don't always paint me as the "bad guy."  Reading his crazy theory was extremely disappointing to me.  It is what it is.

I do not "always paint you as the bad guy".  I have always had a great deal of respect for the knowledge you bring to the table.  But lately, you have become a bit "crotchety".

When the bulk of a response is just demeaning and derogatory insults, perhaps it is time to take a break.

Surely it is not worth all the emotional investment...

PW

[MileHigh]

PW:

Pushing 100 thread pages to get Brad and others to understand how an inductor works and you get this from Brad:

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[Part 1 from Brad]

If R=0, then the current will climb at a steady rate fo all time-right?--no-wrong.
If the flow of current from T=0 is going to rise at a steady state,then the apposing current generated from the CEMF will also rise at a steady state. So what dose that mean for the current induced by the applied voltage?

[Part 2 from Brad]

No,this has not been covered already.

The CEMF is created by the changing magnetic field,which is due to the increasing current over time,that was induced when the voltage was placed across the inductor
This CEMF creates a current flow that is in the opposite direction to that of which the applied voltage induced. The value of the current flow produce by the CEMF is less than that induced by the applied voltage. It you take the peak current value that will be flowing at the 5th time constant,and you subtract from that the peak current value of the first time constant,you are left with the calculated reverse current produced by the CEMF. As you  can see,the current produced by the CEMF ,is less than that of the induced current by the applied voltage. This means the remaining difference is flowing through the coil at the end of the first time constant. The greatest amount of CEMF is produced at T=0,and so the greatest amount of reverse current is produced. This is why the inductor draws the least amount of current at T=0-because the difference between the revers current from the CEMF,and the induced current from the applied EMF ,is at a minimum.

The CEMFs value,and so the value of reverse current,is dependant on how much the magnetic field is changing over time. As the magnetics field change over time slows,less reverse current is produced,as the CEMF value is less. This is why the current induced by the voltage starts to rise over time.

If the current is going to continue to rise-such as it would in your question,then the magnetic field would continue to increase at a steady rate. If the magnetic fields change in time is a constant (as it would be for your ideal coil),then the CEMF would also be at a steady value-as Poynt has answered.

The magnetic fields rate of change over time  in a coil with no resistance,remains at a constant value,and that value is what it was at T=0--the instant the ideal voltage was placed across the ideal coil.
The current value will never increase from what it was as T=0,as the magnetic fields change over time remains at a constant value,and so the self induced EMF also remains at a constant value-->and there for,the reverse current also remains at a constant value.

So,regardless of what you believe, the answer to you question is--the current will not increase any higher than it was at T=0--regardless of the time the voltage is applied to the coil for.

Brad

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After nearly 100 thread pages and finally answering the famous question as well as all of us responding to hundreds of secondary questions and assuming that Brad finally had a decent grasp of the material, we get the comments above.  I can barely comprehend some parts of the prose because it sounds to me like near-gibberish.  However, it appears to be pretty clear that he believes that there is a "tangible reverse current" due to the CEMF somewhere in the mix when you connect a battery or EMF source to a coil.

Hence my frustration, and myself and Brad had a little mutual trash talk.  I am very tempted to just walk away.

MileHigh

[picowatt]

MH,

I believe the "opposite" current that Tinman is discussing is with reference to the induced voltage that creates opposing currents as per the definition of CEMF.  But again, I never read that to mean he believed the CEMF actually reversed the flow sufficiently to "charge the battery" so to speak.

As for the rest of what he is saying, well, that is why I suggested he consider looking into superconductors.

All conductors are inductors, and according to what he is saying, current could not flow through a length of superconducting wire (or at least no more than flows at T=0).  So we kinda' know that can't be right.

There is nothing wrong with leading a horse to water, but...

PW

[tinman]

author=MileHigh link=topic=16589.msg487109#msg487109 date=1466824385]

Yes, a coil will produce a CEMF when you connect a battery up to it.  And the true definition of CEMF is based on the rate of the changing current flowing through the coil.

That is correct,and the CEMF is never the same value as the EFM,as you have stated on more than one occasion now that the EMF and CEMF are the same value ,you are wrong when you state that about inductors and motors.'

The bottom line is that it is the battery that causes current to flow into the coil, and any talk about the CEMF causing current to flow into the battery, tangible or hypothetical, is wrong.  We are talking about a simple single current loop here.

No, one here has ever stated that current will flow back into a battery--this is a misleading comment by you,and you should retract it.
If you had bothered to take the time to read what i said,you would have seen that the reverse current value(the self induced current) is subtracted from the current induced by the voltage that is placed across the coil.

Brad can talk trash too, so don't always paint me as the "bad guy."  Reading his crazy theory was extremely disappointing to me.  It is what it is.

If your talking about what we are discussing here,now,about the self induced current,then it is not trash talk--it's just beyond your means of understanding.

There is nothing wrong with making a very strong point sometimes, especially when it would appear almost nothing registered going the polite route for all these years.  You won't even tell him in simple terms that he is wrong sometimes, like you are going to faint or something.  Even though it is not your style, ultimately it's counter-productive for him.  If I didn't scrap with him, he would still be completely lost like he was at the beginning of this thread.  Direct talk sometimes has its merits.

The only one here that is lost,is you MH,and that has been made apparent time after time.
You just cant handle the fact that i have been told by the top guys here ,that i am correct,and you are wrong.

In the final end game, if Brad is going to have his crazy theories, live and let live.  It's just a chat forum.

The only crazy here,is you MH.


Brad