MH's ideal coil and voltage question

[tinman]

A post from Magneticitist on the JT 101 thread

What I find curious about the whole 'Ideal' scenario no matter how useful it may be in real world applications.. An Ideal inductor is said to dissipate or radiate 0 energy, so technically it only passes current by putting faith in Ohms law's ability to handle the number 0.

I would think that in an ideal voltage source, connecting to an ideal inductor, nothing at all would happen because the voltage cannot waver, and the lack of resistance in the inductor would cause an infinite current were it not for an ideal inductor being unable to dissipate energy. If it cannot dissipate energy it perfectly contains on faith, we cannot possibly observe this energy and it might as well be at rest with no charge.

So even in the fantasy realm of imaginary voltage sources and coils that are ideal, an inductor can do no work unless it actually becomes something we cannot call 'ideal'. further evidence against this paradox of passing infinite current at 0 resistance.

MHs response to some one posting there thought's--and good ones at that.

I am just letting you know as a courtesy that you clearly have no idea what you are talking about.

So now myself,EMJ,Wattsup and Magneticitist are wrong,and MH is yet to post an answer to his own question,nor seems that he is willing to provide any information or answers to other simple questions asked of him.


Brad

[tinman]

You are lost Brad and you should take my advice and start from scratch.  And like usual you are completely baffling because some big clues were presented to you and they passed right through you like you weren't even there.  I am giving you a 10% chance to get it right.

Quote:
The time constant τ is an indicator of how long current takes to increase from zero to its steady-state value.
Here is a useful rule of thumb:
For most practical purposes, we may assume that all quantities in a DC RL circuit have reached their steady-state values after five time constants.

So if a circuit has a time constant of 1 millisecond, then it will take about 5 milliseconds for the circuit's currents and voltages to reach their steady-state values.
Since one time constant is equal to L÷R, we can write this rule of thumb as an equation:
Time to reach steady state ≈ 5×L÷R

So MH,if your !very large! 5 henry coil had a resistance value of say 5 ohms,then it would take 1 second to reach it's time constant,and 5 seconds to reach a steady state current flow.

If your 5 henry coil had just .0001 ohms resistance,then it would take 50,000 seconds to reach it's time constant,and 250,000 seconds to reach a steady state of current flow.

As your coil is ideal,it has no resistance.
So i ask again--how are you going to calculate the time constant of your ideal coil>?


Brad

[MileHigh]

The answer is that there is no time constant.   A variation on the same question was already answered.

That's it, from this point on you can moan and groan and whine and complain all you want.  A better scenario is you tasking yourself with this:

1.  Brad gets up the learning curve and understands the original question and then answers it correctly all by himself and clearly demonstrates that he understands what he is doing.

If you try and make a good sincere effort of it but don't get there, then good show.  If you get there then great show.  But if you just whine for an answer and sit on your fanny and complain then you are going to have to hope that a guru comes along and spoon feeds you.  But of course if you are spoon fed then chances are in two weeks you will be a blank slate.

It's up to you.

[allcanadian]

In an ideal voltage source the source Emf would be fixed and an ideal inductor would have virtually no losses. It seems to me no current could flow because the moment a charge tried to moved due to the ideal voltage source Emf the ideal inductor would produce an equal and opposite Cemf to oppose it. Ideally if the source Emf is always instantaneously opposed by the inductors Cemf then nothing can move, a stalemate.


AC

[Magneticitist]

@AllCanadian   seems a reasonable deduction that follows logic. welcome to the club of having no idea.