MH's ideal coil and voltage question

[picowatt]

So if we could achieve this perfect coupling/flux cutting,then the CEMF should be equal to the EMF that created it. In this case,no current would flow?

I would think that if you could achieve perfect flux coupling/cutting geometries, using an ideal conductor, you would create an inductor with infinite inductance from which it follows that the current flow over time would be infinitely small.

PW

[MileHigh]

Well that was boring MH,as i have already answered the question using the very formula you just used. Perhaps go back say 200 posts,and have a look.

I think the agony here,is having to keep going over the same stuff an endless amount of times with you.

Brad

I am not so sure about that.  I think it's safe to assume that you never solved an integral in your life and you definitely did not go to the integral calculator web site.

The first three seconds of the question were solved using both the integral and differential equations for a coil in no time flat.

The point being that there was no need for all of the agony, and likewise even the useful tools of using visualizations and analogies and all that stuff was not really necessary.  If you actually understood how a coil actually works, and you were familiar with and understood the two equations, then you yourself could have answered the full question in ten minutes flat without all of the drama and the totally ridiculous false technical arguments that you relentlessly put up as obstacles to learning.  All that you had to do was apply the standard equations for a coil.

Will you learn from this experience?  Unfortunately, I honestly doubt you will.

[poynt99]

I see it like this, and I could be wrong of course.

The voltage across the coil terminals does not change, it is determined by the voltage source. But the induced cemf is in series opposing with the voltage source Vin, and its value is determined by the frequency of Vin and the inductance L.

So, from this perspective the induced cemf is usually not equal to the applied emf (Vin). It is usually lower.

[MileHigh]

I see it like this, and I could be wrong of course.

The voltage across the coil terminals does not change, it is determined by the voltage source. But the induced cemf is in series opposing with the voltage source Vin, and its value is determined by the frequency of Vin and the inductance L.

So, from this perspective the induced cemf is usually not equal to the applied emf (Vin). It is usually lower.

I think that you are just going to confuse Brad with that diagram because he is going to see the CEMF being opposite the EMF and his is going to say again that there is no voltage across the coil.

I am puzzled why you would say the CEMF is not equal to the applied EMF. 

its value (the induced CEMF) is determined by the frequency of Vin and the inductance L.

More like the induced current is determined by the frequency of Vin and the inductance L.

I am not sure where you are going with this, but here is a fact that I think we can agree on:

The voltage across the inductor is clamped to the applied EMF voltage, and it doesn't matter if the applied EMF is a DC value or some kind of variable frequency and amplitude AC value.

If you agree with this, then the CEMF is always equal and opposite to the applied EMF.

[poynt99]

I think that you are just going to confuse Brad with that diagram because he is going to see the CEMF being opposite the EMF and his is going to say again that there is no voltage across the coil.

I don't think he will assume that. I believe he knows that even though the induced emf (cemf) is opposite in polarity to that of the applied voltage, it will almost always be less, and therefore there will still be a net applied emf and resulting current.

I am puzzled why you would say the CEMF is not equal to the applied EMF. 

The EMF is applied by the user, while the cemf is self-induced; VL = L x di/dt. So according to the equation, the induced cemf can be any value and will vary depending on the frequency and inductance. The applied EMF never changes its value.

More like the induced current is determined by the frequency of Vin and the inductance L.

I believe that when there is an induced current, there is always an associated induced emf.

I am not sure where you are going with this, but here is a fact that I think we can agree on:

The voltage across the inductor is clamped to the applied EMF voltage, and it doesn't matter if the applied EMF is a DC value or some kind of variable frequency and amplitude AC value.

Yes, but this is a series circuit as well as a parallel circuit, and the induced cemf would be as I depicted.

If you agree with this, then the CEMF is always equal and opposite to the applied EMF.

As I mentioned above, the induced cemf can be any value, and is dependent on the input frequency and the inductance. I don't see any rules being broken here so help me out. Where am I going wrong?