MH's ideal coil and voltage question

[tinman]

You are correct, it is not dissipated.  That which cannot be dissipated is either stored in, or retrieved from, the magnetic field.  It is what inductors do using and obeying the laws of inductance...

We are going on what, 130 years or so of modern man investigating, defining, and verifying the operation of inductors?  All manner of wire types, geometries, resistance and capacitance, use at frequencies into the THz region, study of inductance in the realm of nano-length conductors, inductors using zero resistance conductors, and all manner of core types have been investigated over those years.

PW

Point taken.

So your answer for the below would be?

[picowatt]

Tinman,


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".

PW

[MileHigh]

author=MileHigh link=topic=16589.msg487413#msg487413 date=1467212939]
Well Mr resonance,i have done this by way of showing that when the BackEMF in a DC PM motor equals the applied EMF,then no current flows,and no BackEMF voltage can be measured--the same applies for every other electronic component. Show me just one other component that will allow for current flow,when there is no potential difference across it's terminals.

Brad

I specifically asked you in no uncertain terms to give an example with a coil, not with a motor.  This same thing has happened before, this is the second time we are doing this.  A spinning motor is a different kind of thing with a different model that is more complex.  The principle difference that comes to mind is that the spinning rotor is an active generator of CEMF and is more akin to a battery than a coil.

So you bait and switch instead of giving a simple, tangible example of CEMF needing to be less than the EMF in a coil for current to flow, because you can't.

Personally, I am not overly interested in this discussion.  There are two equations that relate the current and voltage for a coil.  No matter how you want to model it, the two equations hold true.  And they have their direct analogies in the real life physical world and nobody questions them.

MileHigh

[partzman]

Tinman,


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".

PW

OK so you are saying that the Cemf is equal to the Emf in polarity and magnitude during the time the inductor current is ramping at the calculated magnitude according to Faraday's Emf law?  IOW, could we say that the Cemf by definition does not exist during this normal operation of the coil?  I can also assume that you are saying that an amount of Cemf is present during the extremely brief wavefront activity when the fields are in the process of reaching their stable levels from T0 and then reduces to zero after the stable induction current is reached. No feedback correction is considered after this point.

If yes, then I could accept this as this fits the experimental results excluding any analysis of the wavefront or initial start. Experiments could then be run that would carefully examine the various voltages and currents and even possibly the fields during the startup wavefront activity which should yield any evidence of both Emf and Cemf interaction.

pm

Edit

[picowatt]

OK so you are saying that the Cemf is equal to the Emf in polarity and magnitude during the time the inductor current is ramping at the calculated magnitude according to Faraday's Emf law?  IOW, could we say that the Cemf by definition does not exist during this normal operation of the coil?

Absolutely not!

If you were to replace the inductor with another voltage source producing an equivalent CEMF of 4 volts, the only way you would be able to measure that there are two 4 volt sources connected in parallel would be to measure the current flowing thru the circuit.  In the case of using two voltage sources, we know the second source is 4 volts when the current flow is zero.  In the case of the 5H inductor, we know the CEMF is 4 volts when we see a rate of change of .8 amps per second happening to the measured current.

  I can also assume that you are saying that an amount of Cemf is present during the extremely brief wavefront activity when the fields are in the process of reaching their stable levels from T0 and then reduces to zero after the stable induction current is reached. No feedback correction is considered after this point.

The CEMF of 4 volts is generated when, and as soon as, the rate of change of the current flow thru the inductor is .8 amps per second.

If yes, then I could accept this as this fits the experimental results excluding any analysis of the wavefront or initial start. Experiments could then be run that would carefully examine the various voltages and currents and even possibly the fields during the startup wavefront activity which should yield any evidence of both Emf and Cemf interaction.

pm

The evidence of the interaction of EMF and CEMF is via the measured .8 amps per second rate of change to the current flowing thru the circuit.  It is the induced CEMF that prevents the rate of change from being faster or slower than the .8amps per second rate, exactly as defined for a 5H inductor with 4 volts applied across it.

PW