MH's ideal coil and voltage question

[tinman]

I am unaware of anyone claiming or discussing that the CEMF is in parallel with di as you depict it in your left hand drawing.  Your right hand model is what has been discussed all along.


Thanks...

PW

OK,now i am confused.
I thought you said back in post 1511 ,that it was the left modle we were using,and was correct.

Quote: Regarding your diagrams, when the 4 volts is applied to a 5H inductor, as soon as the rate of change of the current flowing thru the inductor reaches .8 amps per second, the generated CEMF would be as in drawing "A".

I dont see the difference between my drawing A,and Partzman's left drawing?

Brad

[Magluvin]

When looking very closely(very narrow time divisions on the scope),i see current rising along with the voltage at T=0,and then the current drop's back down to 0,and then rises again from 0 to follow our exponential curve. So this is either the voltage is instantaneous across the inductor,and these little ceramic resistors have some sort of lag time,or current flows instantly due to winding capacitance,and then drops back to 0 when that capacitor is full,and then current starts to flow ?.

Not to sure on that one,but something is happening before current flow starts due to induction.

I will whip up a quick video to show you guys what i am seeing,and maybe one of you know what is going on?.


Brad

That first current rise is most likely the capacitance of the coil taking on current neglecting the impedance. Like Tesla says about the bifi coils, that the capacitance of the coils charges up upon input as if the inductance is non existent, and the only opposition to the charge up is the coils resistance. A single winding coil has a very tiny capacitance compared to a bifi, but enough to see what you are seeing.

Mags

[picowatt]

OK,now i am confused.
I thought you said back in post 1511 ,that it was the left modle we were using,and was correct.

Quote: Regarding your diagrams, when the 4 volts is applied to a 5H inductor, as soon as the rate of change of the current flowing thru the inductor reaches .8 amps per second, the generated CEMF would be as in drawing "A".

I dont see the difference between my drawing A,and Partzman's left drawing?

Brad

Regarding your two drawings, I believe we were debating the correct polarity of the CEMF at the time, and my answer regarding that was and is that the topmost drawing is correct with regard to the CEMF polarity when di=.8A/s.  As well, your drawings do not indicate the CEMF Vsource, it was assumed to be internal to the inductor you drew and that the +/- indicators for CEMF were just indicated measurement points with regard to the polarity debate. 

Somewhere buried back in the noise I stated that the best model of an inductor was a conductor in series with a variable Vsource (all conductors being an inductor, and using a conductor removes the redundancy of having an "inductor" inside an "inductor model").

I believe there has been confusion caused by the discussion of CEMF polarity, which was debated for some time using parallel connected Vsources and the like.

The model I have been discussing all along is Partzman's "inductor in series with a Vsource" model, his right most model.  If he were to make the change to his notation "C)" as I indicated, it would describe exactly what I have been trying to portray.  Faraday, Lenz, the math, and the negative feedback mechanism, all work as discussed given that one change to his drawing notes.   



PW

[Magluvin]

That first current rise is most likely the capacitance of the coil taking on current neglecting the impedance. Like Tesla says about the bifi coils, that the capacitance of the coils charges up upon input as if the inductance is non existent, and the only opposition to the charge up is the coils resistance. A single winding coil has a very tiny capacitance compared to a bifi, but enough to see what you are seeing.

Mags

And furthermore, if an ideal inductor does not have capacitance, how will that figure into what comes first, the chicken or the egg?

Mags

[tinman]

And furthermore, if an ideal inductor does not have capacitance, how will that figure into what comes first, the chicken or the egg?

Mags

Yes Mag's

At the moment of placing a voltage across the inductor,both the current and voltage rise together--for a very short period of time.
As far as i can make out.i would agree with you,in that the capacitance of the windings is being charged first--but you have to narrow the time divisions on the scope right down to see this brief rise in current from T=0.

And yes-How will having no winding capacitance effect the outcome?

The thing is now,we know there is going to be a difference between an ideal coil,and a non ideal coil.


Brad