He became of #metoo target, due to his own human error. As I already said - I do not agree. Such issues shall be resolved in/by court, not by directorate of MIT - by literally burning all his work, by punishing his students, not actually punishing himself.
Please do yourself and anybody else a favor: get hold of a copy of "Fields and Waves in Communication Electronics" by Ramo, Whinnery and VanDuzer and read the first four pages of chapter 4 (The electromagnetics of circuits)...
I guess you really like that book.
It was my textbook in college 37 years ago for "Electromagnetic Fields and Waves" EECS117A, B, and C. The teacher was Theodore Van Duzer.
As an argument I was referring to scientific paper having peer review and corrections. All you have in return is youtube video with introduction "Hello, hello, hello", no written content and no peer review? Whatta crooked mirrors world you are living in?!
QuoteWhat I see is that they both find that the voltage is dependent on the path, and that when placed on the outside of the loop the voltmeters - applied to the very same two points - give different and opposite phase reading.What?!! Your whole proof is two voltmeters showing different signs?
QuoteQuote"what's the summary field (integral E.dl ) of the loop E = E.coloumb + E.induced?" You did not gave clear answer. Is it zero or not?Here's the answer, assuming that with 'summary' you mean circulation along the circuit's path: the circulation of E_total (integral of (E_coloumb + E_induced) . dl along the circuit's path is equal to minus the time derivative of the flux of B linked by said path.
Yes, it's Faraday's law.
So you refuse to name number because you either do not know it of refuse to acknowledge it being zero?
QuoteIt was my textbook in college 37 years ago for "Electromagnetic Fields and Waves" EECS117A, B, and C. The teacher was Theodore Van Duzer.
Woah, how was he?
The reason I'm bringing RWvD up so many times is that it has a really nice discussion on the origin of KVL and KCL from Maxwell's equations, and of course the fact that ogden seems impervious to reading it.
I have a question. Why wouldn't a simple loop of wire show that "Kirchhoff is for the birds"? (Or even a straight wire)
Also, in one of his videos does Lewin say something like "The oscillioscope on the left measures the voltage across the left resistor." How does he know which one it is measuring?
I agree the book is pretty good. I have referred back to it myself when I realize that I forgot some basic things and it immediately refreshed my memory with it's basic and direct approach. It does require vector calculus, so maybe not for everyone. That's just the nature of the subject.
The peer-reviewed scientific paper backing Lewin's "Hello hello hello" videos is Romer's paper. I had hoped it was clear.
Quote"what's the summary field (integral E.dl ) of the loop E = E.coloumb + E.induced?" You did not gave clear answer. Is it zero or not?Oh, for... ****'s sakes!
It's not zero. The value depends on the time-varying flux: it is equal to minus the time derivative of the flux of B linked by said path. Didn't I just tell you that?
You want a value? In the case of Lewin's experiment, IIRC, it's 1V.
Quote"3) Do you agree that integral E.dl for this circuit is zero at any given time of observation?"Absolutely not.
Do you realize that the circuit you are proposing is just Lewin's ring with one resistor?
After all, when you compute the circulation of E_total = E_conservative + E_induced you get the sum of the circulation of E_conservative which is zero and all that's left is the circulation of E_induced. Everything checks out.
After all, when you compute the circulation of E_total = E_conservative + E_induced you get the sum of the circulation of E_conservative which is zero and all that's left is the circulation of E_induced. Everything checks out.
Wait... E.conservative in the resistor is zero even when on it's terminals is 1V? Are you sure?
After all, when you compute the circulation of E_total = E_conservative + E_induced you get the sum of the circulation of E_conservative which is zero and all that's left is the circulation of E_induced. Everything checks out.
Wait... E.conservative in the resistor is zero even when on it's terminals is 1V? Are you sure?
I was talking about the circulation. You have to close the loop.
Fever has gone up, I will check again tomorrow, if I survive the night :-)
Fever has gone up, I will check again tomorrow, if I survive the night :-)
I hope you get better soon.
Yes, get better soon Sredni. Thank you for sharing your insights and knowledge in this thread.
The only thing you have to do is imagine the magnetic field as a electric field that is circulating around the changing magnetic flux lines.
Once you do that you have only electric fields acting on electrons and those are always conservative so you never get multiple answers for what voltage is between two points.
And this voltage happens to be the exact same voltage voltmeters are showing.
Its just a different way of calculating the same thing, except that this way gives less confusing answers (Particularly in this kind of cirucit)
The two voltmeters will only measure the same voltage if the voltmeters and their connecting wires are outside the field region or somehow shielded or arranged so that the field does not affect the measurement. Fine, but that is not this experiment. This experiment is set up to demonstrate Faraday's law and non conservative fields.
Meanwhile I will sum-up our discussion about "1V AC box + resistor":
While measuring 1V AC voltage coming out of the box with voltmeter/scope, we cannot discern - source is transformer, piezo device or just AC generator powered by chemical battery (we agreed that electrons are the same long ago in this thread). Kirchoff's circuit law (KVL) holds for AC voltage source + resistor *only* when AC voltage is generated by anything but transformer or other kind contraption ruled by Faraday's law. When we have transformer in a box, KVL does not hold anymore. To know - KVL holds or not, we have to look inside the box, otherwise we may be mistaken. This is what you are claiming? Anybody else agreeing?
This is exactly why the other "less scientific" definition of voltage (The one about how many electrons there are in one spot) is used in circuit analysis and pretty much everywhere else where you need to actually calculate something.
QuoteMy way of looking at this box+resistor debate: if black box is able to produce AC 1V alone, I name it EMF source - disregarding it is transformer or just DC-fed AC generator. If I connect resistor, I close the loop, AC 1mA current is flowing and integral E.dl around the loop is zero. There is no magic, just quite simple logic and law of conservation of energy. Do you agree?
No. This is the root of your problem in understanding Faraday. You start with the assumption that integral of E.dl around a loop is zero to prove your thesis that integral of E.dl around the loop is zero.
KVL does not work anymore, and that's the point in saying that Kirchhoff is for the birds.
In short, the loop, the way it is, is unlumpable.
Lumpable means that I can measure the same voltage regardless of the position of the voltmeters.
What we have is a loop antenna. There is a reason why loop antennas are connected by two-wire transmission lines.
The specified conductor length of 1000000 meters is not ideal.
Conductor length should be between 121,250 and 242,500 meters at the specified frequency of 0.0003 MHz.
Why would you do that? The changing magnetic field produces an electric field. The electric field lines are circles around the magnetic field as shown in post #16:
https://www.eevblog.com/forum/chat/does-kirchhoffs-law-hold-disagreeing-with-a-master/msg2003414/#msg2003414
If you have electric field lines that form a loop, as in this case, you have a nonconservative field.
So you don't have two voltmeters connected to same point showing different voltages? This is what happens in the experiment. Or are we supposed to imagine that it doesn't?
The two voltmeters will only measure the same voltage if the voltmeters and their connecting wires are outside the field region or somehow shielded or arranged so that the field does not affect the measurement. Fine, but that is not this experiment. This experiment is set up to demonstrate Faraday's law and non conservative fields.
You seem to be claiming that a voltmeter only measures an electric field caused by separation of charges. For example, you have to move charges on the gate of the input FET of the voltmeter to make it read a voltage, I guess is what you mean.
But the voltmeter can't tell you what separated the charges. It could be a battery, it could be a solar cell, it could be a thermocouple, it could be a hall effect device, it could be a loop of wire surrounding a changing magnetic flux, or it could be a loop of wire rotating in a static magnetic field, to name a few possibilities. The voltmeter cannot distinguish the charge separation caused by the electrostatic scalar potential from the charge separation caused by all the different other types.
In this case, the wires connecting the voltmeter are passing through a region that has a non-zero electric field. That electric field, interacting with the charge in the wire, will give you a different reading on the voltmeter depending on the path the wires take through that field.
*You* have problem, not me. You say that resistor with voltage drop have zero E field inside. That means that integral E.dl over it is zero meaning that it does not have voltage drop on it! It's paradox, don't you see?
What?! TL;DR. You did not even answer.
I will try again.
1) Does KVL hold when inside box is DC battery? 2) Does KVL hold when inside box is battery-powered AC generator? 3) Does KVL hold when inside box is piezo-based 1V AC voltage generator? 4) Does KVL hold when inside box is transformer?