MH's ideal coil and voltage question

[MileHigh]

MH

We have already done this with your ideal coil and ideal voltage.
We know the coil has a resistance value of 0 ohms--or no resistance.
What do you think it is that stops the current going straight to an infinite value,as soon as the voltage is placed across it?.
Why dose it take 3 seconds to reach a current of only 2.4 amp's,and not shoot up to an infinite amount of current flowing through that inductor.
What is the !reactance! in inductive reactance?-->what is reacting to what?
What is !self inductance! ?

I have the feeling that this is just your way of making me waste my time on something that is already very clear--except to you it seems.
So i have voted not to fall for this !waste of time! ploy by you,and instead,i give you a video that should make it very clear to you. As you will see,the circuit to show the effective CEMF is quite simple,and im sure i could show what he explains in the video.

I hope you listen to this video very carefully,and then you will understand that if the CEMF was equal to the EMF that produced it,there would be no current flow,as there would be no voltage drop/or potential difference across the inductor.

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

But even then,i have a feeling we are going to see you !once again! try and change physics to suit your needs.

Brad

Brad:

There is nothing in that clip to back up what you are saying, it's just standard theory.

You are stalling, and in fact reading between the lines I think you are panicking.  You are panicking because you think you can talk the talk but when you are asked to walk the walk you come up short.

So, again, in your own words, give us some simple and fully explained examples that back up your proposal that the CEMF is less than the EMF in a simple inductor circuit and the difference between the EMF and CEMF is a requirement for the current flow.  You have to give actual values for everything and explain it.

No stalling and monkeyshines are going to work.  Give some examples just like I gave two examples that I fully explained in my own words with all of the variables defined.

MileHigh

[MileHigh]

MH,

CEMF is typically used with reference to inductance.

As such, I believe most of us understand CEMF to be more so along the following:

A current flowing thru a conductor creates a magnetic field.  A portion of that magnetic field induces a rate of change dependent voltage into that same conductor.  The polarity of that induced voltage opposes the initial current flow thru the conductor.  It is that induced voltage, in opposition to the initial current flow, that is referred to as CEMF.

Can you provide a reference citing an example of your usage of CEMF with regard to resistors?

PW

The only reference I have right now is that Wikipedia link:

https://en.wikipedia.org/wiki/Counter-electromotive_force#cite_ref-Graf_1-0

The counter-electromotive force (abbreviated counter EMF, or CEMF),[1] also known as the back electromotive force, is the voltage, or electromotive force, that pushes against the current which induces it.

I believe in your case it may simply be a case of not seeing the forest for the trees.  We are so used to thinking about CEMF in terms of an inductor, that we forget about the basic bare-bones definition for CEMF.  CEMF is just a manifestation of what happens to a two-terminal device when we push current through it.

Step back for a second and let's look at the term "counter-electromotive force."  What does it really mean?  It means that a black box is capable of generating some voltage if you push some current through it.

I love this YouTube guy Lasseviren1.  One of his clips pertaining to EMF is this:

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

You don't have to watch it but I attached a still frame from the clip to this posting.  You can see how he uses the symbol for little batteries next to the inductors to represent the CEMF.

So look at one of his little inductors with the CEMF battery next to it.  What if we surround that inductor with a black box?  What if while you are not looking we swap the inductor for a resistor and pump current through the black box?  In that sense, all that you can say if you take a snaphot of the box is that something inside the box is generating counter-EMF.

In summary, CEMF is not necessarily restricted to inductors.  Arguably any device that sustains a voltage drop in a current loop is a device that is manifesting CEMF.

MileHigh

[MileHigh]

As for your 'all four walls are fixed and immovable' in your cart analogy, if any single one of the walls is used as a backstop for the spring, then that wall becomes part of the energy dissipation system.( In reality, since all four walls are all part of the same entire mass of the trough, then the whole trough is part of the energy dissipation.)
You can not compress any spring from one side only. Try it without an anchor point like one of the walls, your spring would just move with the force applied to one side.

Go ahead, try to compress a spring by applying a force to one side without a backstop becoming an essential part of the system of components needed for the energy transfer required to compress it.

You don't need a concrete trough. Just a spring, your hand and .... whatever else is NEEDED to compress the spring.
Now I agree that most of the energy, even in a real world system, will get stored in the spring, but not all. The spring itself, unless ideal, will dissipate some of the compression energy it receives through heat due to lattice stress and displacement.
Only in an idealized world can perfect power transmission and storage take place.  Sadly we don't live in that world, we live in the real world, with circuit losses incurred and components that will never be 'ideal'.

I am just using a simple idealized model.  In that model there is no movement in any of the four concrete walls of the trough.  The spring is between the moving cart and the end of the trough.  As the cart moves forward at a constant velocity the spring gets compressed.  That is like energizing an electrical inductor with a constant voltage source.

I will use a similar example to yours to demonstrate I understand what you mean.

If you are in a house, and you are holding a large spring against a wall and you move forward with your body and compress it, where does the energy go?   Most of it goes into the spring, but the gyprock wall in the house will flex and absorb some of the energy also.  So the wall itself is like a second spring.

If you are outside and do the same thing against a concrete wall, the concrete wall will not flex and absorb any of the energy.  In this case all of the energy goes into the spring.

[tinman]

The only reference I have right now is that Wikipedia link:

https://en.wikipedia.org/wiki/Counter-electromotive_force#cite_ref-Graf_1-0

The counter-electromotive force (abbreviated counter EMF, or CEMF),[1] also known as the back electromotive force, is the voltage, or electromotive force, that pushes against the current which induces it.

I believe in your case it may simply be a case of not seeing the forest for the trees.  We are so used to thinking about CEMF in terms of an inductor, that we forget about the basic bare-bones definition for CEMF.  CEMF is just a manifestation of what happens to a two-terminal device when we push current through it.

Step back for a second and let's look at the term "counter-electromotive force."  What does it really mean?  It means that a black box is capable of generating some voltage if you push some current through it.

I love this YouTube gut Lasseviren1.  One of his clips pertaining to EMF is this:

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

You don't have to watch it but I attached a still frame from the clip to this posting.  You can see how he uses the symbol for little batteries next to the inductors to represent the CEMF.

So look at one of his little inductors with the CEMF battery next to it.  What if we surround that inductor with a black box?  What if while you are not looking we swap the inductor for a resistor and pump current through the black box?  In that sense, all that you can say if you take a snaphot of the box is that something inside the box is generating counter-EMF.

In summary, CEMF is not necessarily restricted to inductors.  Arguably any device that sustains a voltage drop in a current loop is a device that is manifesting CEMF.

MileHigh

MH
You have defiantly lost the plot.

First up,a resistor limits the flow of current--it is a restrictor.
An inductor resists a !change! in current-both an increase and decrease-inductive reactance.

I am in no way,shape,or form,going to bow down to your stupidity,and waste my time on something that should be common knowledge to you--as it is with everyone else here.
And to think,you thought you had the smarts to give EMJ a hard time on his understandings about inductors and coils--and me for that matter.

If you choose to argue the point with PW,Poynt,Loner,Hoptoad,and most everyone else on this forum,and they have the time to argue against such an idiotic argument,then so be it--but i will have no part in this rubbish.

I dont know what planet you are on,or if you fell into a drum of coolaid,and drank your way out,but if the CEMF was equal and opposite to the EMF,then the total voltage across the inductors terminals would be 0v,and no current would flow.

Your probably smashing out emails left,right,and center to PW and Poynt ATM,trying to get them to join you in your coolaid swimming pool of CEMF,but this foolishness is not for me.


You have yourself a great time MH,but i am done with your repeated stupidity,and re-writing of physics.


Brad

[hoptoad]

snip...
In summary, CEMF is not necessarily restricted to inductors.  Arguably any device that sustains a voltage drop in a current loop is a device that is manifesting CEMF.

MileHigh

I agree with you that CEMF is not restricted to inductors and can manifest from any change in current. As I explained in my previous post, technically any changing current at any level can produces a CEMF. Just as CEMF is not necessarily restricted to inductors, capacitance is not restricted to capacitors and resistance is not restricted to resistors. That's common knowledge, because none of our components are ideal, they have a blend of all those characteristics.

Only in an ideal world can we have ideal scenarios. Most here seem to know that capacitors leak, everything has some inductance and resistance is ever present. It is the degree to which a characteristic of a component contributes to a particular phenomena that we determine its practical purposes and what we expect it cause to happen in a circuit.

If I asked any electronics buff to give me an inductor, he is not going to hand me a capacitor or resistor and say this will do the same thing. Because he knows that each component is specifically designed to enhance one electrical characteristic and minimize the others.

Resistance is ever an present phenomenon, in both steady and changing fields in a circuit, while CEMF is an emergent force that manifests only with changes in electrical/magnetic fields, and disappears in steady unchanging fields. Resistance and CEMF are not the same thing.