### Author Topic: #562 – Electroboom!  (Read 75632 times)

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#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #875 on: January 10, 2022, 04:25:41 am »
Does KVL hold? Yes!

$- 0.3798V + 0.1A \times 5\Omega + 0.1A \times 5\Omega - 0.6202V = 0$

What BS excuse are you going to craft now?

How about the one given by Maxwell?

Quote
The  theory  of  conjugate  conductors  has  been  investigated  by
Kirchhoff,  who  has  stated  the  conditions  of  a  linear  system  in
the  following  manner,  in  which  the  consideration  of  the  potential
is  avoided.

(1)  (Condition  of  'continuity.')  At  any  point  of  the  system
the  sum  of  all  the  currents  which  flow  towards  that  point  is
zero.

(2)  In  any  complete  circuit  formed  by  the  conductors  the  sum
of  the  electromotive  forces  taken  round  the  circuit  is  equal  to
the  sum  of  the  products  of  the  current  in  each  conductor  multi-
plied by  the  resistance  of  that  conductor.

So, if the consideration of potential is avoided, then we need to eliminate the potential difference between points A and D from your beautiful equation, which becomes:

$0.1A \times 5\Omega + 0.1A \times 5\Omega = 1V ≠ 0$

KVL fails.

And this agrees exactly with what he says in the video @12:19:

Quote
It is always worth reminding ourselves that our voltmeter connected between nodes A and B, and the conditions are that the voltmeter measurement PATH does not intersect the time varying field, the voltmeter will not indicate the potential difference between A and B, rather it will indicate the OHMIC voltage difference between nodes A and B.

As I predicted, you didn't understand, by a long, long shot!  Either that or we have another member of team Lewin in denial!

1) Half_Circuit != Complete_Circuit.  But more important:

2) Do you even know what this quote means "is always worth reminding ourselves that our voltmeter connected between nodes A and B, and the conditions are that the voltmeter measurement path does not intersect the time varying field, the voltmeter will not indicate the potential difference between A and B, rather it will indicate the ohmic voltage difference between nodes A and B."  Well, it means that if you measure with the voltmeter without cancelling the induced EMF in the probes due to the varying magnetic field,  what you read in the multimeter is the voltage drop in the resistance.  This is the mistake that Lewin made in his demonstration.  But wait, there is more:

3) Starting at minute 13:00 Trevor Kearney says : "...if it were physically possible to align a voltmeter measurement path with the physical path A-X-B, the indication would then be the same as the calculated potential difference...".  Do you know why?  Because there will not be induced EMF in the voltmeter probes!  This is exactly what I have shown a bunch of times with my experiments.  And this is also what Lewin failed to do or even understand in his experiment.

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#### Sredni

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##### Re: #562 – Electroboom!
« Reply #876 on: January 10, 2022, 05:04:22 am »
This video from Trevor Kearney debunks many, if not all your claims:

Have you watched it yet?  Pay attention on how many potential difference voltages between nodes A and B he calculates: one.

This is the second time I write this in this thread.

Dude, that's Trevor Kearney. He's probably the most active "Lewin defender" on youtube (go read his posts on Electroboom's channel if you don't believe me). He's "Armchair Physics Nobel Laureate" number one in fromjesse's scale. It's funny that you bring his videos in your defense (like fromjesse linking those videos from Purdue university, not understanding that professor Melloch has the same views as Lewin).
Trevor is computing the ELECTRIC SCALAR POTENTIAL difference. One of the two components of the actual voltage.

And, no, in the case of my wobbly circuit, not even him will be able to find a closed analytical solution. You have to go numerical. But that's not the point. The point is that you are not able to find 'your' voltage between any two points of a simple resistive circuit linking a variable magnetic flux. Not a very useful theory, isn't it. Especially considering that you should apply that even to simple resistive circuits NOT linking a variable magnetic flux, but just being in the same universe as a variable magnetic flux region. (Let me guess: you have no idea what I am talking about, right?)

Yes, I really meant "zero internal resistance voltmeters" because I did consider the 10 meg internal resistance of my voltmeter when I showed you that running a voltmeter with its probes around a magnetic core is NOT the same thing as running a zero resistance wire around it. But you did not understand that either

Really?  It looks to me that you didn't watch the video!  Are you in denial again?  Here, I added to his right hand side circuit equivalent, the equivalent circuit for the left hand side:

Let us calculate the voltage from the right:

$V_{AB} = 0.3798V - 0.1A \times 5\Omega = - 0.1202V$

Now the voltage from the left:

$V_{AB} = 0.1A \times 5\Omega - 0.6202V = - 0.1202V$

Are the calculated values identical?  Yes!

Does KVL hold? Yes!

$- 0.3798V + 0.1A \times 5\Omega + 0.1A \times 5\Omega - 0.6202V = 0$

What BS excuse are you going to craft now?

Ok, I had not watched the video, because I cannot see images and videos from my laptop. Now I logged in (for the first time) with my phone and while posting is a PITA (is this why you quote entire posts? Can't select parts of text?), at least I can see videos and images to the posts I respond.

Yes, if you take A UNIFORM RESISTIVE RING the voltages you measure from the exterior between two points on a diameter are bound to be equal because they are given by

Resistance of arc * current in loop

And if the arcs have the same length you end up with the same voltage. The flux off axis requires the development of surface charge that will compensate for the nonuniformity of the induced field in the region occupied by the ring.

This is not the two resistor lewin ring but it's okay, I'll go along with it.

Now PICK TWO POINTS THAT ARE NOT ON A DIAMETER, and show us how KVL is working.

For example pick A and B such that going from A to B will require three quarter of circumference and going from B to A will require a quarter.

Compute the voltages now.
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#### bsfeechannel

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##### Re: #562 – Electroboom!
« Reply #877 on: January 10, 2022, 05:33:13 am »
Well, it means that if you measure with the voltmeter without cancelling the induced EMF in the probes due to the varying magnetic field,  what you read in the multimeter is the voltage drop in the resistance.  This is the mistake that Lewin made in his demonstration.  But wait, there is more:

There's no EMF induced because the circuit the probes establish with the resistance and the meter has no varying magnetic field inside the area delimited by the closed path constituted by them. This is Faraday's law. That's why the only voltage that you'll measure is the voltage across the resistor, which is the current through it times its resistance.

Lewin probed this area with a calibrated hall sensor in his previous lecture and showed beyond any doubt that the area was free from varying magnetic fields.

Everyone repeated his experiment and obtained the same results.

That's why he's right.

Quote
3) Starting at minute 13:00 Trevor Kearney says : "...if it were physically possible to align a voltmeter measurement path with the physical path A-X-B, the indication would then be the same as the calculated potential difference...".  Do you know why?

Yes.

Quote
Because there will not be induced EMF in the voltmeter probes!

It's because the probes of your meter would be in such a convenient path where the total EMF produced by the two loops they establish with each resistor will be the same and will coincide in value with the scalar potential difference between the two points.

Quote
This is exactly what I have shown a bunch of times with my experiments.

Congratulations! You showed that not only you can measure two different voltages across the same two points of a circuit whose area is subjected to a varying magnetic field, but also that you can measure a third voltage.

I'll recommend you for the Nobel Prize of Physics of 2022.

Quote
And this is also what Lewin failed to do or even understand in his experiment.

Poor Lewin.  Oh, well, at least this didn't disprove the fact that you CAN measure two different voltages across the same two points of a circuit whose area is subjected to a varying magnetic field and that KVL is bird food.

#### bsfeechannel

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##### Re: #562 – Electroboom!
« Reply #878 on: January 10, 2022, 05:36:56 am »
Oh, now I see the tactic clearly.

Their tactic is to be debunked multiple times in every single page of the thread. Endless amusement.

#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #879 on: January 10, 2022, 05:49:18 am »
This video from Trevor Kearney debunks many, if not all your claims:

Have you watched it yet?  Pay attention on how many potential difference voltages between nodes A and B he calculates: one.

This is the second time I write this in this thread.

Dude, that's Trevor Kearney. He's probably the most active "Lewin defender" on youtube (go read his posts on Electroboom's channel if you don't believe me). He's "Armchair Physics Nobel Laureate" number one in fromjesse's scale. It's funny that you bring his videos in your defense (like fromjesse linking those videos from Purdue university, not understanding that professor Melloch has the same views as Lewin).
Trevor is computing the ELECTRIC SCALAR POTENTIAL difference. One of the two components of the actual voltage.

And, no, in the case of my wobbly circuit, not even him will be able to find a closed analytical solution. You have to go numerical. But that's not the point. The point is that you are not able to find 'your' voltage between any two points of a simple resistive circuit linking a variable magnetic flux. Not a very useful theory, isn't it. Especially considering that you should apply that even to simple resistive circuits NOT linking a variable magnetic flux, but just being in the same universe as a variable magnetic flux region. (Let me guess: you have no idea what I am talking about, right?)

Yes, I really meant "zero internal resistance voltmeters" because I did consider the 10 meg internal resistance of my voltmeter when I showed you that running a voltmeter with its probes around a magnetic core is NOT the same thing as running a zero resistance wire around it. But you did not understand that either

Really?  It looks to me that you didn't watch the video!  Are you in denial again?  Here, I added to his right hand side circuit equivalent, the equivalent circuit for the left hand side:

Let us calculate the voltage from the right:

$V_{AB} = 0.3798V - 0.1A \times 5\Omega = - 0.1202V$

Now the voltage from the left:

$V_{AB} = 0.1A \times 5\Omega - 0.6202V = - 0.1202V$

Are the calculated values identical?  Yes!

Does KVL hold? Yes!

$- 0.3798V + 0.1A \times 5\Omega + 0.1A \times 5\Omega - 0.6202V = 0$

What BS excuse are you going to craft now?

Ok, I had not watched the video, because I cannot see images and videos from my laptop. Now I logged in (for the first time) with my phone and while posting is a PITA (is this why you quote entire posts? Can't select parts of text?), at least I can see videos and images to the posts I respond.

Yes, if you take A UNIFORM RESISTIVE RING the voltages you measure from the exterior between two points on a diameter are bound to be equal because they are given by

Resistance of arc * current in loop

And if the arcs have the same length you end up with the same voltage. The flux off axis requires the development of surface charge that will compensate for the nonuniformity of the induced field in the region occupied by the ring.

This is not the two resistor lewin ring but it's okay, I'll go along with it.

Now PICK TWO POINTS THAT ARE NOT ON A DIAMETER, and show us how KVL is working.

For example pick A and B such that going from A to B will require three quarter of circumference and going from B to A will require a quarter.

Compute the voltages now.

Sure, why not.  I picked the nodes A and C as shown in the figure:

Since the circuit is symmetric along the horizontal axis with respect to the magnetic flux, the induced EMF between nodes A and C on the top right quarter is half what Trevor Kearney calculated in the video, or 0.3798V/2=0.1899V.  Also the resistance is now also half or 2.5 ohms.  Conversely, the induced EMF in the rest of the ring is 1V-0.1899V=0.8101V and the resistance is 7.5 ohms.  This is the equivalent circuit we need to solve using KVL:

You can calculate either using the left or the right of the equivalent circuit.  The result is the same:

$\begin{array}{l} V_{AC} = 0.1899V - 0.1A \times 2.5\Omega = - 0.0601V \\ V_{AC} = 0.1A \times 7.5\Omega - 0.8101V = - 0.0601V \\ \end{array}$

« Last Edit: January 10, 2022, 05:51:52 am by jesuscf »
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#### ogden

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##### Re: #562 – Electroboom!
« Reply #880 on: January 10, 2022, 06:00:04 am »
Now everybody can see what cultism does to the brain. He states:

Faraday's law of induction doesn't care about wires, leads, probes, whatever. They're irrelevant. They're not even mentioned in the law.

Actual law:
Quote
Faraday's law states that there is emf on the conductive loop when the magnetic flux through the surface enclosed by the loop varies in time.

If that is not conclusive enough, one can watch Dr.Lewin's YT video about Faraday's law.

Whole post for the records, in case bsfeechannel wakes-up and finds that he contradicted even to himself:

Lewin's cultists truly believe that 1/4 of the transformer wire turn do not have 1/4 of EMF on it because when they try to measure using voltmeter, by placing voltmeter leads next to wire they measure, they see 0V - as expected.

If, as expected, the voltage measured across a piece of wire is zero, it is because it IS zero. Any other conjecture about that voltage is absolutely moronic in the context of our discussion.

Quote
It is obvious that Faradays' law of induction do not care - it is test circuit or voltmeter leads, but Lewin's cultists are stubborn, they claim that they know better and for some reason voltmeter leads are not influenced by time-varying magnetic field of experiment, only circuit.

Faraday's law of induction doesn't care about wires, leads, probes, whatever. They're irrelevant. They're not even mentioned in the law.

What Faraday's law of induction says is that the TOTAL EMF around a CLOSED ARBITRARY path, any path, whatever path in whatever portion of the SPACE, is proportional to the rate of change of the magnetic field INSIDE the area, whatever area, delimited by the aforementioned closed PATH.

So, if your meter, your probes and your wire under test constitute a closed PATH that delimit an AREA where the magnetic field doesn't change or, better yet, where there's none, the EMF is NULLE (in Latvian), i.e. ZERO, нуль, صفر, 零, μηδέν.

So there's no EMF, no belief, no cultism, no Lewin. It is only the theory, which by the way was extensively reviewed and tested by the most brilliant minds of our recent times, agreeing with practice.

Lewin, the Lewin cultism, the belief, and the phantasmagorical EMF that you claim is present in the wires is just an artificial construct that only exists in the brain-damaged mind of a KVLiar. No scientist, professor or author, dead or alive, will agree with you.

Quote
In short - fact that Lewin and his cultists struggle to properly measure EMF, do not mean it does not exist.

We, you and all the other cabrones like Mehdi, Mabilde, Jesse and the RSD dude, measure and the voltage is zero (or to be precise it is the current times the resistance of the wire), exactly like the theory predicts.

I told you in the other discussion we had three years ago that you don't understand electromagnetism because you're a "circuity" guy. You're limited to wires. No wonder, Kirchhoff was obsessed with them. They're the essence of his laws. Maxwell's equations made us understand the phenomenon of electricity and magnetism beyond wires. The universe is plenty of an unfathomably large number of electromagnetic events and it is not even wired.

So free your mind and give Lewin a kiss in the cheek.

#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #881 on: January 10, 2022, 06:46:51 am »
Now everybody can see what cultism does to the brain. He states:

Faraday's law of induction doesn't care about wires, leads, probes, whatever. They're irrelevant. They're not even mentioned in the law.

Actual law:
Quote
Faraday's law states that there is emf on the conductive loop when the magnetic flux through the surface enclosed by the loop varies in time.

If that is not conclusive enough, one can watch Dr.Lewin's YT video about Faraday's law.

You are correct: team Lewin is even contradicting basic concepts that Lewin taught correctly!
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#### bsfeechannel

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##### Re: #562 – Electroboom!
« Reply #882 on: January 10, 2022, 07:26:04 am »
Now everybody can see what cultism does to the brain.

Yes. And in the case of the KVLiars, the cognitive impairment seems to be irreversible.

Quote
Actual law:
Faraday's law states that there is emf on the conductive loop when the magnetic flux through the surface enclosed by the loop varies in time.

Since the EMF will be there even if you don't have a conductor (otherwise propagation would be impossible), the most accepted version of Faraday's law is:

The electromotive force around a closed path is equal to the negative of the time rate of change of the magnetic flux enclosed by the path.

Instead of the conductive loop you can also have a conductive plate or block. Faraday's law doesn't care.

Quote
If that is not conclusive enough, one can watch Dr.Lewin's YT video about Faraday's law.

Here you can see how we are independent and we verify things ourselves, unlike KVLiars who take whatever stupid assertion that comes out of Mehdi's or uncle RSD's butt at face value.

Quote
Whole post for the records, in case bsfeechannel wakes-up

I never sleep.

Quote
and finds that he contradicted even to himself:

More likely to find KVLiars spreading misconceptions and pseudo-science.

#### Sredni

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##### Re: #562 – Electroboom!
« Reply #883 on: January 10, 2022, 10:28:06 am »

Quote
Compute the voltages now.

Sure, why not.  I picked the nodes A and C as shown in the figure:

Since the circuit is symmetric along the horizontal axis with respect to the magnetic flux, the induced EMF between nodes A and C on the top right quarter is half what Trevor Kearney calculated in the video, or 0.3798V/2=0.1899V.  Also the resistance is now also half or 2.5 ohms.  Conversely, the induced EMF in the rest of the ring is 1V-0.1899V=0.8101V and the resistance is 7.5 ohms

That is not voltage. That is scalar potential difference.
It turns out that Trevor uses V to denote the scalar potential difference (what I now call phi) and U_path to denote voltage (what I call V_gamma).

You can ask himself, if you want.

"Hi Trevor, is this video a demonstration that Lewin is wrong in saying that voltage is path dependent? Or are you computing the scalar potential difference which happens to be independent of path, but is different from voltage?"

And see what he replies.

Chances are that he will link you to his last video "Scalar potential difference a questionable choice for the true voltage between the test nodes in Dr Lewin's Experiment"

(In case you are wondering, no I haven't seen all of Trevor's videos from start to finish. I love his passion and I know we share the same positions from what he writes in the comments on YouTube, bit his videos are too long and too low volume for me to watch from start to finish - I just skim through them. But here is a screenshot that tells the whole story:

see, how he makes a distinction between scalar potential difference and voltage?)
« Last Edit: January 10, 2022, 01:44:43 pm by Sredni »
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#### Sredni

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##### Re: #562 – Electroboom!
« Reply #884 on: January 10, 2022, 10:33:15 am »
All instruments lie. Usually on the bench.

#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #885 on: January 10, 2022, 03:44:09 pm »

Quote
Compute the voltages now.

Sure, why not.  I picked the nodes A and C as shown in the figure:

Since the circuit is symmetric along the horizontal axis with respect to the magnetic flux, the induced EMF between nodes A and C on the top right quarter is half what Trevor Kearney calculated in the video, or 0.3798V/2=0.1899V.  Also the resistance is now also half or 2.5 ohms.  Conversely, the induced EMF in the rest of the ring is 1V-0.1899V=0.8101V and the resistance is 7.5 ohms

That is not voltage. That is scalar potential difference.
It turns out that Trevor uses V to denote the scalar potential difference (what I now call phi) and U_path to denote voltage (what I call V_gamma).

You can ask himself, if you want.

"Hi Trevor, is this video a demonstration that Lewin is wrong in saying that voltage is path dependent? Or are you computing the scalar potential difference which happens to be independent of path, but is different from voltage?"

And see what he replies.

Chances are that he will link you to his last video "Scalar potential difference a questionable choice for the true voltage between the test nodes in Dr Lewin's Experiment"

(In case you are wondering, no I haven't seen all of Trevor's videos from start to finish. I love his passion and I know we share the same positions from what he writes in the comments on YouTube, bit his videos are too long and too low volume for me to watch from start to finish - I just skim through them. But here is a screenshot that tells the whole story:

see, how he makes a distinction between scalar potential difference and voltage?)

In that problem the scalar potential difference is equal to the true voltage between nodes A and C because the magnetic flux is defined as:

$\varphi (t) = 1.0t[Wb]$

So the magnitude of the induced EMF is a constant 1V, which is not a function of time.  We are solving a DC circuit!
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#### thinkfat

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##### Re: #562 – Electroboom!
« Reply #886 on: January 10, 2022, 04:34:16 pm »
In that problem the scalar potential difference is equal to the true voltage between nodes A and C because the magnetic flux is defined as:

$\varphi (t) = 1.0t[Wb]$

So the magnitude of the induced EMF is a constant 1V, which is not a function of time.  We are solving a DC circuit!

What does that have to do with anything? It's just a construct to make the calculation easier to follow.
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#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #887 on: January 10, 2022, 06:46:31 pm »
In that problem the scalar potential difference is equal to the true voltage between nodes A and C because the magnetic flux is defined as:

$\varphi (t) = 1.0t[Wb]$

So the magnitude of the induced EMF is a constant 1V, which is not a function of time.  We are solving a DC circuit!

What does that have to do with anything? It's just a construct to make the calculation easier to follow.

So is my calculation of the potential difference between nodes A and C correct or no?   Is that the voltage VAC or not?  Just asking, because I see yet another 'moving the goalposts' fallacy coming from Sredni.
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#### Sredni

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##### Re: #562 – Electroboom!
« Reply #888 on: January 10, 2022, 07:20:44 pm »
I did not even check, but if it's scalar potential difference you are after, and you get the same result as Trevor then it might be correct.
But it is only half of the story

Voltage = scalar PD + induced voltage

The scalar PD obeys kvl because it's the result of the conservative field generated by the displaced surface and interface charge. In Lewin's ring it is largely due to the charge accumulated at the resistors' ends.
You just need to sum the induced voltage to get the 'true voltage', ie (minus) the path integral of the TOTAL electric field.

Note in the case of the symmetric  uniform resistive ring  things are a bit different in that Etot = Eind and you only need surface charge when you place the ring off-center.
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#### bsfeechannel

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##### Re: #562 – Electroboom!
« Reply #889 on: January 11, 2022, 03:48:49 am »

I never sleep.

Brother!

Don't worry. I have a life.

So is my calculation of the potential difference between nodes A and C correct or no?   Is that the voltage VAC or not?  Just asking, because I see yet another 'moving the goalposts' fallacy coming from Sredni.

If you think that the scalar potential difference will save you, think again.

#### ogden

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##### Re: #562 – Electroboom!
« Reply #890 on: January 11, 2022, 04:58:35 am »
If you think that the scalar potential difference will save you, think again.

To prove that KVL is for birds, Lewin's cultists simply omit energy source in their circuit schematics - as if current is appearing out of nowhere. Very clever! BTW 0.5V + 0.5V = 1V which is voltage of "invisible EMF source", so... how to say... you did just prove KVL! Congrats! Glad you can learn too. Next time don't forget to include transformer secondary in your schematics. Hopefully you know the symbol.
« Last Edit: January 11, 2022, 05:21:53 am by ogden »

#### bsfeechannel

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##### Re: #562 – Electroboom!
« Reply #891 on: January 11, 2022, 05:42:07 am »
To prove that KVL is for birds, Lewin's cultists simply omit energy source in their circuit schematics - as if current is appearing out of nowhere.

This is not a concern of KVL. It only states that the voltages around a loop must add up to zero. End of story. In the case of Lewin's circuit they don't.

Quote
Very clever! BTW 0.5V + 0.5V = 1V

Which is even worse, since 1 V is farther away from 0 V than 0.5 V is.

« Last Edit: January 11, 2022, 05:43:39 am by bsfeechannel »

#### ogden

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##### Re: #562 – Electroboom!
« Reply #892 on: January 11, 2022, 05:57:08 am »
To prove that KVL is for birds, Lewin's cultists simply omit energy source in their circuit schematics - as if current is appearing out of nowhere.

This is not a concern of KVL. It only states that the voltages around a loop must add up to zero. End of story. In the case of Lewin's circuit they don't.

Quote
Very clever! BTW 0.5V + 0.5V = 1V

Which is even worse, since 1 V is farther away from 0 V than 0.5 V is.

Next thing Lewin's cultists do - choose convenient to their fallacy, polarities. They can easily claim that 1V chemical battery in series with 1K resistor sum-up to 2V because I*R added to 1V of the battery equals 2V, so KVL per their logic fail.

#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #893 on: January 11, 2022, 06:37:52 am »
To prove that KVL is for birds, Lewin's cultists simply omit energy source in their circuit schematics - as if current is appearing out of nowhere.

This is not a concern of KVL. It only states that the voltages around a loop must add up to zero. End of story. In the case of Lewin's circuit they don't.

Quote
Very clever! BTW 0.5V + 0.5V = 1V

Which is even worse, since 1 V is farther away from 0 V than 0.5 V is.

Next thing Lewin's cultists do - choose convenient to their fallacy, polarities. They can easily claim that 1V chemical battery in series with 1K resistor sum-up to 2V because I*R added to 1V of the battery equals 2V, so KVL per their logic fail.

They will always come up with a new fallacy, I'll bet on it!
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#### Sredni

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##### Re: #562 – Electroboom!
« Reply #894 on: January 11, 2022, 07:52:46 am »
If you think that the scalar potential difference will save you, think again.

To prove that KVL is for birds, Lewin's cultists simply omit energy source in their circuit schematics - as if current is appearing out of nowhere. Very clever! BTW 0.5V + 0.5V = 1V which is voltage of "invisible EMF source", so... how to say... you did just prove KVL! Congrats! Glad you can learn too. Next time don't forget to include transformer secondary in your schematics. Hopefully you know the symbol.

...aaaaand we are back to square one.

5  + 3 = 8.  Vs 5 + 3 - 8 = 0

and the inability of KVLers of seeing a difference between lumped and unlumpable circuits.

But hold that thought about current coming out of nowhere.
In the case of the perfectly symmetric uniform resistive ring we have Etot = Eind (this is exact in the 2D case). That is, since Ecoul=0, the scalar potential difference is zero everywhere on the ring.
And in fact KVLers proudly show that their radial measures of "voltage" are all zero.
In their view K"V"L holds because the sum of all zero "voltages" is zero.

But now its their turn to ignore the energy source.
They have all "voltages" zero, and "current coming out of nowhere". So they are forced to switch definition of voltage and invent the distributed battery+resistor element.

1-1+1-1+1-1+1-1+1-1+1-1+1-1+1-1=0

Does that mean that the radial measure that shows zero "voltage" is not measuring the true voltage, now?
« Last Edit: January 11, 2022, 08:11:02 am by Sredni »
All instruments lie. Usually on the bench.

#### thinkfat

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##### Re: #562 – Electroboom!
« Reply #895 on: January 11, 2022, 08:34:29 am »

So, if the scalar PD between A and D is the "true voltage" in the Lewin ring, then what @bsfeechannel showed above is a proper model for Dr. Lewins setup, right?
That means one can replace the induced EMF with a voltage source between A and D with the "true voltage" and that is then the energy source of the circuit?
But if this is really a proper model for Dr. Lewins circuit, it must also reproduce the meter readings from the experiment, right?
Only it doesn't. Hm. So, apparently it is not a proper model for Dr. Lewins circuit.

Maybe it's a proper model for the @jesuscf circuit? Apparently so, because he measured it with a few percent of error. He cannot say where this error comes from, but lets not go there now. But he also admits that if the probing wires were to follow a slightly different path, the error would increase.
So, @jesuscf found one single, very special path on which the $V_{AD}$ coincided with the computed scalar PD and yes, if in his circuit he replaced the induced EMF with a voltage source between A and D, the outcome would not change. But if he connected a second voltmeter between A and D on any other path, the whole model would collapse.

Everybody likes gadgets. Until they try to make them.

#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #896 on: January 11, 2022, 03:38:31 pm »

So, if the scalar PD between A and D is the "true voltage" in the Lewin ring, then what @bsfeechannel showed above is a proper model for Dr. Lewins setup, right?
That means one can replace the induced EMF with a voltage source between A and D with the "true voltage" and that is then the energy source of the circuit?
But if this is really a proper model for Dr. Lewins circuit, it must also reproduce the meter readings from the experiment, right?
Only it doesn't. Hm. So, apparently it is not a proper model for Dr. Lewins circuit.

Maybe it's a proper model for the @jesuscf circuit? Apparently so, because he measured it with a few percent of error. He cannot say where this error comes from, but lets not go there now. But he also admits that if the probing wires were to follow a slightly different path, the error would increase.
So, @jesuscf found one single, very special path on which the $V_{AD}$ coincided with the computed scalar PD and yes, if in his circuit he replaced the induced EMF with a voltage source between A and D, the outcome would not change. But if he connected a second voltmeter between A and D on any other path, the whole model would collapse.

It looks to me that you never learnt how to do basic circuit analysis!  Also, are you implying that I forged the results of my experiments?  There is a very simple way for you to prove it: repeat the experiment yourself and post the results here.
Homer: Kids, there's three ways to do things; the right way, the wrong way and the Max Power way!
Bart: Isn't that the wrong way?
Homer: Yeah, but faster!

#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #897 on: January 11, 2022, 03:51:18 pm »
If you think that the scalar potential difference will save you, think again.

To prove that KVL is for birds, Lewin's cultists simply omit energy source in their circuit schematics - as if current is appearing out of nowhere. Very clever! BTW 0.5V + 0.5V = 1V which is voltage of "invisible EMF source", so... how to say... you did just prove KVL! Congrats! Glad you can learn too. Next time don't forget to include transformer secondary in your schematics. Hopefully you know the symbol.

...aaaaand we are back to square one.

5  + 3 = 8.  Vs 5 + 3 - 8 = 0

and the inability of KVLers of seeing a difference between lumped and unlumpable circuits.

But hold that thought about current coming out of nowhere.
In the case of the perfectly symmetric uniform resistive ring we have Etot = Eind (this is exact in the 2D case). That is, since Ecoul=0, the scalar potential difference is zero everywhere on the ring.
And in fact KVLers proudly show that their radial measures of "voltage" are all zero.
In their view K"V"L holds because the sum of all zero "voltages" is zero.

But now its their turn to ignore the energy source.
They have all "voltages" zero, and "current coming out of nowhere". So they are forced to switch definition of voltage and invent the distributed battery+resistor element.

1-1+1-1+1-1+1-1+1-1+1-1+1-1+1-1=0

Does that mean that the radial measure that shows zero "voltage" is not measuring the true voltage, now?

Yes, jump to conclusions without getting the correct equivalent circuit of the modified setup and solving it first.  That is the favorite procedure of team Lewin!
Homer: Kids, there's three ways to do things; the right way, the wrong way and the Max Power way!
Bart: Isn't that the wrong way?
Homer: Yeah, but faster!

#### jesuscf

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##### Re: #562 – Electroboom!
« Reply #898 on: January 11, 2022, 04:11:36 pm »

I never sleep.

Brother!

Don't worry. I have a life.

So is my calculation of the potential difference between nodes A and C correct or no?   Is that the voltage VAC or not?  Just asking, because I see yet another 'moving the goalposts' fallacy coming from Sredni.

If you think that the scalar potential difference will save you, think again.

Here, I fixed it for you.  I am pretty sure you'll never understand it!

Homer: Kids, there's three ways to do things; the right way, the wrong way and the Max Power way!
Bart: Isn't that the wrong way?
Homer: Yeah, but faster!

#### ogden

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##### Re: #562 – Electroboom!
« Reply #899 on: January 11, 2022, 04:57:52 pm »
So, if the scalar PD between A and D is the "true voltage" in the Lewin ring, then what @bsfeechannel showed above is a proper model for Dr. Lewins setup, right?
No. It is just proper copy of Dr.Lewin's improper model which omits EMF source in the circuit schematics. Just because some could not find proof of EMF by measuring improperly probing segment of the loop, does not mean it does not exist.

Quote
That means one can replace the induced EMF with a voltage source between A and D with the "true voltage" and that is then the energy source of the circuit?
No. EMF is induced in the conductive elements of the loop. You can't calculate or measure voltage between two points of the circuit and declare it as voltage *source*. It could be just voltage *drop* with source somewhere else. You really shall consider to learn (more about) Electromagnetic Induction and Faraday's law, start with https://youtu.be/nGQbA2jwkWI?t=1.

Smf