MH's ideal coil and voltage question

[tinman]

 author=MileHigh link=topic=16589.msg483533#msg483533 date=1462796493]
 

You are just making phony dismissive arguments that take you off track.  The point of the exercise is perfectly clear:  To understand how an inductor works.

No MH. You are making claims you cannot back up,as you do not have access to an ideal inductor.

A real inductor can be 99.99% identical to an ideal inductor.

99.99% of infinity is an infinite amount away from ideal MH. This may shock you ,but the difference between 99.99% and absolute can be extremely large.
When i asked what the L/R time constant was,you said there isnt one.
With your non ideal coil(being the one that is 99.99% close to ideal)there is an L/R time constant,and so that coil has a finite L/R time constant,where as the ideal coil has either a time constant of 0,or it is infinite. These two values are far from your 99.99% close enough is near enough coil,as it is not even close.

Like i said,you should have thought about your question a little better.

Ideal voltage sources exist right now within certain limitations.  A good bench power supply is an ideal voltage source.  A car audio amplifier is an ideal voltage source that can output The Star Spangled Banner as an ideal voltage.  I explain that all on the other thread.

They are not ideal at all.
An ideal voltage dose not change--at all,when a load is placed across it-not even by .0000001 of a volt. The ideal power supply would need an ideal transformer,and ideal FWBR,and all other components would have to be ideal--including the power station,the grid supply,and the meter on your house.
All these factors you fail to take into account when you stated an ideal voltage and an ideal inductor.

The real-world test can easily be done as explained on the other thread.

You cannot do a real world test on fictional components and values.

The only limitation is that the real-world inductor will behave a tiny smidgen differently from the ideal inductor.

No-the difference is !infinite!--you just dont get this,do you ?.


Brad

[poynt99]

If the time constant is infinite for maximum current through the ideal inductor,then that means that no current flows through the inductor--ever,because if it takes an infinite amount of time to reach maximum current flow through the coil,then it also takes an infinite amount of time to reach a 10% value of maximum current flow through the ideal inductor,and it takes an infinite amount of time to reach 1% of the maximum amount of current flow through the ideal inductor--and so on. So it will take an infinite amount of time before current even starts to flow--so there will never be any current flow through the ideal inductor.

My blown universe post was a bit of a ruse. In fact it implied the opposite of what would theoretically happen, that is, "nothing".

[poynt99]

How do you calculate the L/R time constant, when there is no R

L/0=infinite

[poynt99]

A sim of an ideal V source across an ideal inductor will crash the sim.

A tiny bit of resistance must be added as the computational resolution is finite.

[MileHigh]

Brad:

<<< No-the difference is !infinite!--you just dont get this,do you ?. >>>

You are just getting belligerent for no reason and you are twisting your logic and not really making sense.

I said that a real-world coil can be 99.99% identical in behaviour to an ideal coil.  That means the difference in their behaviour on the bench will be one part in 10,000.  That's pretty damn similar.

Any good bench power supply with a big capacitor on the output, a huge transformer or huge switching power supply, and a well-designed negative feedback control system to maintain a constant output voltage will be 99.99% identical to an ideal voltage source so the same argument applies.

The point being again that discussing ideal coils or ideal voltage sources is not far fetched at all.

This is the real topic of discussion:  a) What is inductance?  b) Demonstrate your understanding of inductance by solving for the current for an ideal inductor in a simple circuit.

That is what you need to focus on.

MileHigh