MH's ideal coil and voltage question

[picowatt]

Absolutely  AC
Ideal means perfect-a losless conversion between EMF-forward current-counterEMF-reverse current.of the same amount.

This would more so describe an ideal inductor that also has an infinite amount of inductance.  As such, when connected across a voltage source, no current would ever flow as the time constant would also be infinite.  An ideal inductor with infinite inductance would appear to be a continuous open circuit when connected in parallel with a voltage source.

Consider the superconducting magnet used in an MRI machine.  Typically, they have a total inductance of around 6000Hy.  They are "charged" very slowly to a couple hundred amps or so with an adjustable current limited source to prevent an excessive overvoltage condition.

So that would mean a dead short when an ideal voltage from an ideal source is placed across the ideal inductor,as as much current would be trying to flow back into the ideal voltage source,as the ideal voltage source is trying to deliver.

My answer stands--you cannot place an ideal voltage across an ideal inductor.

You seem to be describing an ideal capacitor with an infinite amount of capacitance.  An ideal capacitor with an infinite amount of capacitance would have an infinite time constant and appear to be a continuous short circuit when connected in parallel with a voltage source.

That's my 2 cents for now.  I've been away and will try to catch up on this thread as time allows.  Very busy...

PW

[Magneticitist]

This would more so describe an ideal inductor that also has an infinite amount of inductance.  As such, when connected across a voltage source, no current would ever flow as the time constant would also be infinite.  An ideal inductor with infinite inductance would appear to be a continuous open circuit when connected to a voltage source.

Consider the superconducting magnet used in an MRI machine.  Typically, they have a total inductance of around 6000Hy.  They are "charged" very slowly to a couple hundred amps or so with an adjustable current limited source to prevent an excessive overvoltage condition.

You seem to be describing an ideal capacitor with an infinite amount of capacitance.  An ideal capacitor with an infinite amount of capacitance would have an infinite time constant and appear to be a continuous short circuit when a voltage is applied across it.

That's my 2 cents for now.  I've been away and will try to catch up on this thread as time allows.  Very busy...

PW

let's say this is true, and it honestly makes a degree of sense even though I disagree in principle..
Wouldn't this mean the inductor is 'perfectly' accomplishing the exact opposite of what it's supposed to be perfectly doing in nature? Wouldn't the EMF and *CEMF be increasing against each other the entire time to infinity? And wouldn't that have to mean a continuously rising current?

How does that not constitute current change?

[minnie]

  This photo is for the Tinman.
   Basically we get too much overunity and have to hand-rear the triplets.
   These are a few of this years pets.
   How about this for a business idea Tinman? Start the manufacture of
   braking systems for overunity machines.
    The one thing Wayne Travis got right on his early plans for his church
   was the provision of a cooling system!!!

[tinman]

I don't see why we should have to take it further than "perfectly and absolutely resists current change".

This automatically means no EMF or counter EMF doesn't it?

What it means ,is that there can be no voltage across the ideal inductor--so yes.
It also means,as i said before,the current would be instant,and infinite--but no current flow. It would be much like supplying each end of a water pipe with water at 40psi. You would have pressure,but no flow.

Brad

[tinman]

Consider the superconducting magnet used in an MRI machine.  Typically, they have a total inductance of around 6000Hy.  They are "charged" very slowly to a couple hundred amps or so with an adjustable current limited source to prevent an excessive overvoltage condition.

You seem to be describing an ideal capacitor with an infinite amount of capacitance.  An ideal capacitor with an infinite amount of capacitance would have an infinite time constant and appear to be a continuous short circuit when connected in parallel with a voltage source.

That's my 2 cents for now.  I've been away and will try to catch up on this thread as time allows.  Very busy...

PW

This would more so describe an ideal inductor that also has an infinite amount of inductance.  As such, when connected across a voltage source, no current would ever flow as the time constant would also be infinite.  An ideal inductor with infinite inductance would appear to be a continuous open circuit when connected in parallel with a voltage source.

Thanks for joining PW.
I have to say that i dont agree with the ideal inductor needing to have an infinite inductance value.
Any iductor that is ideal is loss less -dose not dissipate power,due to having no resistance or capacitance. It converts or stores 100% of the energy it receives--ideal. Being the case,the current created when the v ideal voltage is placed across the ideal inductor,would create an CEMF and current of the same value--100% conversion--ideal.

Due to the fact that the voltage is also ideal,the source of that voltage must also be ideal.
Lets say it's an ideal battery,meaning that that battery could deliver 4 volts across any load without a voltage drop. The battery would also have to be ideal,and there for would have no internal resistance,and would not dissipate power by way of waste heat,or radiated energy of any type.

Once this ideal voltage source is hooked across the ideal inductor,as soon as any magnetic field started to form,it would produce an exact opposite,in the way of CEMF and current--ideal conversion. We know this to be true in an ideal situation,as everything has an equal and opposite reaction. In a non ideal situation,some of that equal and opposite is lost to heat due to resistance and parasitic capacitance--but not in an ideal situation,which is what the original question states the inductor and voltage source is--ideal.

The result would be an instant and infinite current build up between the ideal voltage source,and the ideal inductor,but no current would flow.And as there is no resistance throughout the circuit,no voltage would appear anywhere across that loop.

It is hard for some to understand what !ideal! mean's,but think about it long enough,and you begin to put all the pieces together.

Every action has an equal and opposite reaction--this dose not change.
And so,in this ideal situation,the CEMF must be equal and opposite to the EMF,and the current produced by the CEMF that apposes the current produced by the EMF must also be equal and opposite,as an ideal inductor dose not dissipate power.


Brad