Brad:

I am sorry but I am going to be nasty here because you deserve it:

<<< I dont know what is going on with you MH,but you need to make up your mind here.
Can a voltage exist across an ideal inductor that has a DC current flowing through it or not?--it's a very simple question,and you can have two answers as you have above. >>>

Just because the current is flowing in one direction you are calling that "DC current?"  This ridiculous nonsense takes its root from my answering the more difficult question and you haven't mastered the concept of what "DC" means relative to talking about coils?





Inductors are all about current changing with respect to time and you pull off this silly stunt because you don't know?



MileHigh

That is not DC current you loonie that is current that is changing in time.

Now we get to see MH redefine DC current.

DC current is a unidirectional current flow MH.

https://en.wikipedia.org/wiki/Direct_current
Direct current (DC) is the unidirectional flow of electric charge. Direct current is produced by sources such as batteries, power supplies, thermocouples, solar cells, or dynamos. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current.[1]

All of this stupid nonsensical idiocy because poor Brad can't make a distinction between constant DC current that does not change with respect to time and current that is flowing in the same direction that does change with respect to time?

Show me the post where you stated constant current MH--you did not.
You clearly stated DC(direct current flow),and no where is direct current describe as constant current flow --you doofuss.

[/b]You are in the corner with a dunce cap on right now.  People reading are aghast.

Look in the mirror MH--Mr dont know what a DC current flow is.


Brad

No Brad, you look in the mirror.  What are you even doing here?  Six years of playing with coils and all that you can do is quote a Wiki entry for DC current.  Because you cannot understand what "DC current" means relative to a discussion about coils, it's clearly showing how truly limited your understanding is.

I was hoping that you would get up the learning curve and be able to answer the question that was posed to others, but clearly there is not a hope in hell.  The gurus won't say anything, but I can assure you they are just as shocked as me.  Or perhaps they aren't shocked at all.

No Brad, you look in the mirror.  What are you even doing here?  Six years of playing with coils and all that you can do is quote a Wiki entry for DC current.  Because you cannot understand what "DC current" means relative to a discussion about coils, it's clearly showing how truly limited your understanding is.

I was hoping that you would get up the learning curve and be able to answer the question that was posed to others, but clearly there is not a hope in hell.  The gurus won't say anything, but I can assure you they are just as shocked as me.  Or perhaps they aren't shocked at all.

No Matter how you try and change things around MH,you clearly quoted DC current,and then you admitted that you meant a constant DC current.
Perhaps be a little more accurate in future.
Its much like giving your address as America,rather than your actual street address--no one is ever going to find you.

So now,how did you define your inductance value with an inductor that has no resistance?
The magnetic field will continue to rise as long as the current continues to rise,and having an ideal voltage source feeding this ideal inductor,the current rise will be infinite,and so will the magnetic field. Induction will never stop. Of course in the real world,we also have resistance ,which limits the flow of current,and so limits the increase of the magnetic field to a set amount.


Brad

Nice that you added in a resistance and dropped the zero capacitance MH,, that changes the question and as such your posted question now is not the question under scrutiny.
False.

I actually explained that and why friction IS within your real world example you have provided.

Where does the force come from that the arms are pushing against to push against the shopping cart MH,, putting the cart before the arms maybe??  and doing that without any feet,,

Why is it that the legs have a larger input than the arms MH? when down here on the surface of the planet where there is gravity,, you know "in the real world"

Since you can not calculate the inductance of a coil with zero resistance and zero capacitance, (you have not been able to show that you can so you must not be able to do it,, is that not your methodology?) then you must not fully understand inductance. ( again more of your methodology)

Ah yes Webby, you are definitely a soul-mate for Brad.  Here we have the poor kid in the grade 11 Physics class that "just doesn't get it" and continuously interrupts the teacher with dumb questions and squanders valuable time from the whole class on a consistent basis.

You are incapable of extracting the relevant information in the story and realizing what the example is actually all about.  The example is just about a force pushing on a mass, and the mass accelerating and pushing back with equal force.  That's all there is to it and the rest of the story is just window dressing to bring home the point that we experience these kinds of things in real life all the time.  It's the same story with the problem student bringing up capacitance in the 5 Henry coil discussion when capacitance has never even been discussed and is not on the table.  It's extraneous noise from the problem student.

You can just keep on being the problem "thread child."

MileHigh

Not that it matters but, back to the shopping cart for a moment...

The frictionless cart will still resist any movement because it has mass, especially if it is full as stated.  Yes, it will move more easily due to being frictionless but, F=MA still applies.

I realize that MH was trying to make a point about electronics so my post makes no difference, I just did not want folks to forget about inertia in the cart example.

Bill

Not that it matters but, back to the shopping cart for a moment...

The frictionless cart will still resist any movement because it has mass, especially if it is full as stated.  Yes, it will move more easily due to being frictionless but, F=MA still applies.

I realize that MH was trying to make a point about electronics so my post makes no difference, I just did not want folks to forget about inertia in the cart example.

Bill

Bill, Imagine the friction with the mother in Law from Sencellus in the trolly;-))


Mass meat's ..................!?

For reference, this is the harder version of the question I answered that Brad made reference to in post 2607:

<<<
Here is the harder version of the question and the answer:

You have an ideal voltage source and an ideal coil of 5 Henrys.  At time t=0 seconds the coil connects to the ideal voltage source.  The voltage source waveform is 20*t^2.  So as the time t increases, the voltage increases proportional to the square of the time.

The question is what happens starting at t = 0

The answer:

The current through the ideal coil starts from zero at time t = 0 and then increases with this formula:  i = 1.33*t^3.

Time..........Voltage.........Current
0...............0.................0
1...............20...............1.33
5...............500.............166.67
10.............2000............1333.33
20.............8000............10666.67
50.............50000..........166666.7

Brad, you need to try to get up the learning curve such that you get to the point where you come back and acknowledge the answer given above is correct.
>>>

And poor Brad thinks I am talking about "DC current" when I am talking about a rising voltage waveform proportional to t-squared and the resultant rising current waveform that is proportional to t-cubed.  The mind boggles.

Quote Brad from post #2607:

<<< Have you lost your marbles MH ?
This whole thing you have been peddling is about how you can place a voltage across an ideal coil,and a DC current will flow through that coil.See below >>>

What's even more of a joke is when I started the process of answering the easier question these were Brad's responses:

<<<
You are the epic failure others claim you to be.
You are a total disaster
Your a fraud.
You epic failure.
You are now the laughing stock of this forum.
>>>

Brad:  Everything you read in your own quoted text above in reality applies to you yourself.  You have been bluffing your way through this whole thing.  It's a farce and a fiasco.

MileHigh

"And poor Brad thinks I am talking about "DC current" when I am talking about a rising voltage waveform proportional to t-squared and the resultant rising current waveform that is proportional to t-cubed.  The mind boggles."


What is an ideal voltage source? Is it not a source that can hold its voltage no matter the load???  So if the ideal inductor is put across the ideal voltage source there should be no rising voltage waveform, as you put it, because the ideal voltage source will maintain its voltage no matter the load. No?? And if the ideal voltage source, as you put it, is directly across the ideal inductors leads.  The only thing that could possibly rise is current, that is if current flows at all considering the argument of cemf being ideal also, that Brad, AC and I have posed issue with.

Mags

The issue of an ideal voltage source varying in time has already been discussed several times on this thread.  Just look at the original question, the ideal voltage source varies with time.  I don't know how ideas like "an ideal voltage source cannot change in time" take hold but apparently they do.  Somebody says it and nobody thinks to question it.

<<< The only thing that could possibly rise is current, that is if current flows at all considering the argument of cemf being ideal also >>>

We are beating an old horse to death at this time.  It's a second strange idea, it's baffling and it and the "fixed ideal voltage source" idea would not last more than eight minutes apiece on a real electronics forum before they were sliced to pieces.

Look at this clip that discusses ideal inductors and brush up on your inductor concepts:

https://www.youtube.com/watch?v=B8CPGiK59f8