MH's ideal coil and voltage question

[tinman]

What does DC current have to do with anything when you put voltage across an ideal coil?   You will have to contemplate that.

You have been given more than enough information to do some hunting and researching on your own so that you answer the question correctly.  You still haven't taken a stab at the full question.

After all this, it still feels to me like there is faint hope that you are going to achieve those two tasks I listed for you with your current attitude.  You never know though like I already said.  I think that you are going to have to hope a guru comes in to help you because I am jumping off the train and switching to passive observer mode.

I hope one day in the not too distant future to see you follow-up on both tasks successfully and demonstrate full competence in this very important subject matter.

MileHigh

The fact that you have dismissed the L/R time constant to answer your original question is troubling.You have dismissed using this method-which is used in any other situation,based on the fact that there is no R value. You know that if you did use this conventional method,that the result would be exactly as myself and Poynt said it would be--there would be no flow of current,due to the infinite time constant value. You have dismissed the method that gives us the time constant required to answer your question correctly. This method (Tau=L/R) is the correct method to use in regards to your question. The fact that it results in no current flowing through the ideal inductor ,is inline with the fact that an ideal inductor dose not dissipate energy. Also to back it up is the fact that we have an ideal voltage of 4 volts across that inductor for a period of 3 seconds. This also states that during this time,no current can be flowing through that inductor,as there is a voltage across it,and as you your self have stated,if a DC current was flowing through that inductor,then there would be no voltage across it--but we have 4 volts across it,and so no current is flowing through it. This also falls in line with Poynts sim test.

All circuits used to make this definition are based around an ideal inductor,but with an added series resistor to simulate the resistance that would exist in a real world inductor. If we are to define the outcome of placing an ideal voltage across an ideal inductor,then there is no reason at all that the series resistor just be removed to obtain the correct evaluation for an ideal inductor.

The only reason you do not wish to use this method of Tau=L/R,is because that then puts you in a position of being incorrect. this being the case,i find that a sad time indeed in the history of this forum,where people come to learn and solve such problems using what we know and undderstand to be correct.

Quote: http://www.learnabout-electronics.org/ac_theory/dc_ccts45.php
When a current is applied to an inductor it takes some time for the current to reach its maximum value, after which it will remain in a "steady state" until some other event causes the input to change. The time taken for the current to rise to its steady state value in an LR circuit depends on:
•The resistance (R)
This is the total circuit resistance, which includes the DC resistance of the inductor (RL) itself, plus any external circuit resistance.
• The inductance of L
Which is proportional to the square of the number of turns, the cross sectional area of coil and the permeability of the core.

I am standing firm on my answers,and i hope Poynt(and others) takes the time to have another look at this,and not just accept your example as a reality.


Brad

[Magneticitist]

guys let's just make a deal and be honest. MH wants to act like you are a complete loony for believing what you do, but I'm fairly sure this is not some extremely rare argument and has been argued before, probably to this very day by many others.. there are others in this thread that share Brads view as well. does that mean MH is wrong? of course not. but until some kind of all ending smoking gun evidence can be presented (which it cannot) what is the point? ok let's say we're using a real R value then. still, what's the point? even plugging in the numbers and calculating for current or the rate of current change, or the voltage, or whatever.. at this point it's just going through the motions.

How about we agree to make a real conscious effort learning about inductors the same way MH did when he was being indoctrinated so long as he agrees to stop using circuit examples with values of 0 and expect a real provable formulaic outcome or omitting variables from formulas altogether.

Then hopefully we can go back to the original topic loool. I'm genuinely interested I mean when do you see me here, that's what I came for and for like 10 pages there it looked like you guys were creeping ever closer to a real provable answer which is what I thought MH had up his sleeve with this whole question thing but oh well can we move on now.

[tinman]

guys let's just make a deal and be honest. MH wants to act like you are a complete loony for believing what you do, but I'm fairly sure this is not some extremely rare argument and has been argued before, probably to this very day by many others.. there are others in this thread that share Brads view as well. does that mean MH is wrong? of course not. but until some kind of all ending smoking gun evidence can be presented (which it cannot) what is the point? ok let's say we're using a real R value then. still, what's the point? even plugging in the numbers and calculating for current or the rate of current change, or the voltage, or whatever.. at this point it's just going through the motions.

How about we agree to make a real conscious effort learning about inductors the same way MH did when he was being indoctrinated so long as he agrees to stop using circuit examples with values of 0 and expect a real provable formulaic outcome or omitting variables from formulas altogether.

Then hopefully we can go back to the original topic loool. I'm genuinely interested I mean when do you see me here, that's what I came for and for like 10 pages there it looked like you guys were creeping ever closer to a real provable answer which is what I thought MH had up his sleeve with this whole question thing but oh well can we move on now.

I started this thread to remove the debate on MHs ideal coil and voltage question from the JT 101 thread,so as discussion on the topic of JTs could continue without unrelated topics being discussed there,and splitting up the thread. But it seems that now capacitors has also taken hold in that thread--perhaps a dedicated thread on capacitors should also be opened.


Brad

[MileHigh]

I will drop in and say this out of frustration:

1.  Talking about DC current through an ideal coil and no resultant voltage drop is meaningless and has nothing to do with this exercise.

2.  When you apply voltage across an ideal coil you get changing and increasing current.  This simple fact is escaping you and as a result you are leading yourself down a garden path.  Just like when you apply voltage across a real coil you get changing and increasing current until the current levels off.

It's pull yourself up by your own bootstraps time, or stick in mud and be wrong and go nowhere time, or wait for a guru to save you time.

[Magneticitist]

This is true I don't mean to disrespect this thread or MH's wishes to avoid further JT discussion... but I have to ask since you two are honestly the best people to ask at this point.. I was eagerly reading
your discussion in the JT thread before this topic and didn't quite realize how far off topic it was actually leading. I guess I may have to try to steal the JT thread back on topic but then I don't want to interrupt the capacitor talk after it has gained some charge. this topic actually has merit too though I suppose, I just don't see how one side could really disprove the other.