MH's ideal coil and voltage question

[partzman]

Because an ideal voltage source has no internal resistance,and that is what makes it ideal.
The ideal voltage source is a series/parallel connection,as there is only two components in the circuit. As that ideal voltage source provides the very same link across the inductor as the piece of non resistant wire dose,then as soon as you hook the ideal voltage source across that ideal inductor,you have just shorted(looped) that ideal inductor.

If the voltage was reduced to 0 volts on the ideal voltage source,the current flow would continue through the loop that now exist in the ideal coil.=,as the voltage source has no internal resistance to impede the current flow.

Ask your self this.
When MH turns his voltage source down to a value of 0 volts,will the current flow continue on?
If not,then explain as to why not--what will impede that current flow,when the complete loop from the ideal inductor across the ideal voltage supply has no resistance ?

Who here can draw the complete circuit,along with the resistance values of that circuit?.


Brad

Let me first answer your question. When the ideal voltage source goes to zero volts, the current in the ideal coil will remain at the level it reached with the previous condition and will stay that way until the ideal voltage source is changed to a different magnitude.

What was confusing is that it appeared you wished to apply an ideal voltage across an ideal coil with an ideal short. This is not equivalent to the circuit as MH proposed.

The circuit diagram is simply an ideal source in parallel with an ideal inductor with no resistance.

partzman

[picowatt]

No, I believe that when the parasitic capacitance is disregarded then the inductors equivalent circuit has it wire resistance in series with its inductance and that entire circuit is closed by an ideal wire just like with an ideal inductor devoid of resistance.

I was agreeing with this as far as the wire resistance of a normal inductor being in series with the inductor, but when you got to the point where you stated "that entire circuit is closed by an ideal wire just like with an ideal inductor devoid of resistance" you lost me.

Are you referring to some circuit in particular or are you stating that the equivalent model for every inductor includes a short circuit across its terminals?

The model for a normal inductor has the wire resistance in series with the inductor.  The model for an ideal inductor removes that series resistor (or places its value at zero).  There is no short circuit across either inductor.

PW

[poynt99]

You were answering my question posted on my circuit diagram Poynt.
How can you say that you were referring to MHs question?

Brad

Well, actually I wasn't. What I was doing which led to my response was the following:

I think use of the term "shorted" when referring to an ideal inductor is not good nor accurate nomenclature.

An ideal inductor simply has zero series resistance. It is not "shorted" in any way, and will not present itself as a "short" if/when a voltage source (ideal or not) is connected across it.

Here I was responding to a post from verpies. Referring to an ideal inductor as being "shorted" brings no practical utility to the discussion other than to add confusion.

You need to think a little beyond what you are Poynt,and draw the circuit as MH said i should,
I have provided the definitions of the ideal voltage from an ideal voltage source,and an ideal inductor.

If an ideal inductor is shorted,so as it becomes an endless loop,can a voltage be measured anywhere across any two points of that(now looped) ideal inductor while a current is flowing through it?.


Brad

What is there that is beyond a voltage source and an inductor in series/parallel? I can draw it out in my head, what am I missing?

Let's throw in an ideal switch as well. What happens when the switch closes?

The second part of your question sounds like Faraday induction with the coil shorted.

Here I was responding to your response. Clearly I am referring to the original circuit, an ideal inductor with an ideal voltage source connected across it. Then I introduce an ideal switch. You said it yourself, "draw the circuit as MH asked you to", to paraphrase. There is nothing more to the circuit, specifically, no short across the inductor.

It seems that you are conflating the series connection of the voltage source with an inductor, with a parallel connection (across a shorted inductor) stipulated by Tinman.

Here verpies misinterprets my post as referring to your circuit diagram with the short. As I explained, that is not what I was referring to.

I would strongly suggest that all focus on the original question and purpose of this thread. I have now given you a clear illustration of the voltage source contained within the question, and reworded it to get directly to the point of the question.

So Brad, or Mags, will you give it a go? That is, plot out the current trace right over top of the voltage trace I posted?

[MileHigh]

What was confusing is that it appeared you wished to apply an ideal voltage across an ideal coil with an ideal short. This is not equivalent to the circuit as MH proposed.

That's classic Brad.  From what I can gather the schematic that he posted did not match his written description from a few posts earlier, creating confusion.

[tinman]

Seemingly yes, if you do not count the ideal wire that shorts the inductor.
Pay attention to this issue and the associated terminology because in my opinion this is the reason why you and MH cannot agree.
Yes, there is no resistance to current flow but there is impedance to current flow.  That is why the current does not become infinite immediately.
Impedance has two components.  Please consider both of them.

Quote
Ideal inductors and capacitors have a purely imaginary reactive impedance:

Verpies
Can you define what they mean by !imaginary!,as this seems to only be associated with ideal inductors,where as non ideal(real world)inductors are always stated as having impedance,without the use of the word !imaginary! .

2nd-
If the ideal voltage source is reduced to a value of 0 volts instantly,but the non resistive link of the ideal voltage source is still across the ideal inductor,will the current continue to flow through the circuit,as there is nothing to impede this current flow.

Brad