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Author Topic: Professor Walter Lewin's Non-conservative Fields Experiment  (Read 253059 times)
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Don't worry about it Poynt.  :)  I'm just getting into everything and try to understand and unify things.  I think we'll understand each other someday.  Let's just have some fun.

Here I post a picture.  The set up is as discussed in this section.  The secondary loop is now squared.  All measurement are decoupled.  Can you guys guess what is the measurement at point 1,2, and 3?  If we have disagreement, then we can check it back with experiment.





   

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My opinion is:

123-1=0
123-2=.9v
123-3=0


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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It's not as complicated as it may seem...
Here I post a picture.  The set up is as discussed in this section.  The secondary loop is now squared.  All measurement are decoupled.  Can you guys guess what is the measurement at point 1,2, and 3?  If we have disagreement, then we can check it back with experiment.

I would, but I don't understand your question, nor how it relates to your diagram.  :-\
   
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My opinion is:

123-1=0
123-2=.9v
123-3=0


you are probably correct if the probes are like Lewin's, but this is vertical/decoupled/normal to the measured loop.

Poynt,

let's say point 123 is the one reference, move the other one around to obtains different measurements.

   
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Refering to:


For me Gibbs is right.
One can't simply consider the two diametrically opposed points of connection as being the terminals of a battery, presenting a potential difference. There is no objective potential difference, not even a potential difference. The voltage is observer dependent.
Induced Emf must be evaluated only along a closed path because it is defined only along a closed path. There is no particular voltage between the two diametrically opposed points until we define the path for the measurement. The fact that the wires connecting the voltmeter are along the B field don't disqualify the rule that want that the emf is defined only along a closed circuit.

If we had a resistance in series with the circular loop and want to know the voltage at the resistance terminals, i.e. the voltage felt by the resistance, we would have to put the voltmeter in parallel with the resistance with no flux crossing in between, in order the resistance and the voltmeter have the same viewpoint, being the same and alone "observer" viewing the same closed path which is both the resistance circuit and the measurement circuit.

The voltmeter being the "observer", it can see only the emf along the closed path of its own measurement circuit. The fact that there is no flux crossing the vertical part of the circuit and the vertical wires are along the B field is an irrelevant data because the emf is given only by dφ/dt, φ being the crossing flux through the surface of the whole circuit.
Here we have 2 loops.
1) We see obviously that some flux crosses the surface of the measurement circuit, as represented by the arrows (presuming the voltmeter is connected to the top).
2) We see that for symmetry reasons, the same flux crosses in equal quantity left and right, so from the voltmeter viewpoint, the resultant flux cancels because each half flux crosses each identical half circuit but in reverse directions. The measure will be zero (1/2*dφ/dt-1/2*dφ/dt).
If one connected a voltmeter directly through the diameter, it will also show zero, for the same reason, and in despite its wires would be othogonal to the B field .

The important point is that an induced emf is defined only on a closed path and that we must never consider that the path could be broken down into independent sections, each one being as a partial source of emf, all being in series. Nature doesn't work this way.
A simple experiment can prove what I say: an single electron near a conductor loop carrying a varying current, doesn't feel any force. It don't move. But if you place billions of electrons around the first loop while imposing them a closed path, they will move. Principle of a transformer. I'm the first surprised.

   

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It's not as complicated as it may seem...
Poynt,

let's say point 123 is the one reference, move the other one around to obtains different measurements.

There isn't enough information on the diagram to answer the question.

What are the resistor values, and which one is which? What is the length of each wire segment? What is the induced emf?
   
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There isn't enough information on the diagram to answer the question.

What are the resistor values, and which one is which? What is the length of each wire segment? What is the induced emf?


All parameter is the same as before.  1V total induced EMF, 100Ohm, 900Ohm, one segment is twice the other which is the diameter of the primary.  I don't think it matter which resistor is which in this case. 



   

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It's not as complicated as it may seem...
Gibbs,

In order to ask your question properly, you must state that the length of the resistors are negligible relative to the length of the wire segments. When all the segment lengths are equal, this is not a requirement. In your example, the segment lengths are NOT equal, therefore you MUST assume that the resistors are negligible in comparison.

Let's assume the resistors are 0.01 inches long. Now your question can be answered.
   

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It's not as complicated as it may seem...


Alright, assuming the scope NEG lead is on terminal "123" (as you stated) and the current CW, the correct answers are as follows:

V1 - V123 = -0.1666V
V2 - V123 = -0.2333V
V3 - V123 = +0.3333V

Note these are calculated values, not opinions. ;)
   

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Alright, assuming the scope NEG lead is on terminal "123" (as you stated) and the current CW, the correct answers are as follows:

V1 - V123 = -0.1666V
V2 - V123 = -0.2333V
V3 - V123 = +0.3333V

Note these are calculated values, not opinions. ;)

 O0

So now you are the one saying Ohm's law doesn't always apply?  ;)


---------------------------
"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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you are probably correct if the probes are like Lewin's, but this is vertical/decoupled/normal to the measured loop.

Ah! Ok.

Then I will change my .9V to .4V  ;)


---------------------------
"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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It's not as complicated as it may seem...
So now you are the one saying Ohm's law doesn't always apply?  ;)
Nope. You're not paying careful enough attention to the diagrams WW.

Look one post above this one of yours where you object to the indicated readings:
http://www.overunityresearch.com/index.php?topic=739.msg21215#msg21215
You will see the diagrams in question above this post of yours.

You state that all 3 voltages will read 0.4V. That is incorrect.

What you are apprently NOT paying attention to on my diagrams, and Gibbs' diagram, is where the probes are connected. Are they directly across the resistors as in my diagrams "V11'" and "V99'"?, or is there a wire segment in between the measurement probes as shown in my diagram "Vda" and Gibbs' "de.jpg" diagram?

Hopefully, once you realize this oversight, you will see that Ohm's law still holds in this case.

Gibbs has reminded you, but in case you missed it, the measurement probes in his diagram are decoupled, even though they don't appear to be.

.99

PS. Ohm's law can appear to be broken when making certain measurements, such as the one shown here in the diagram:
http://www.overunityresearch.com/index.php?topic=739.msg21406#msg21406
But this can only happen when the measurement is made in-plane and as shown.
« Last Edit: 2012-04-01, 23:13:38 by poynt99 »
   

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It's not as complicated as it may seem...
Then I will change my .9V to .4V  ;)

 :D
   

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It's not as complicated as it may seem...
In light of the way things have gone so far for some of the participants in this thread, I thought it fitting to re-post these words of wisdom:

The experiment tells more about the experimenter than the physics. (Not pointed only at .99)

I couldn't agree more.  O0
   
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Alright, assuming the scope NEG lead is on terminal "123" (as you stated) and the current CW, the correct answers are as follows:

V1 - V123 = -0.1666V
V2 - V123 = -0.2333V
V3 - V123 = +0.3333V

Note these are calculated values, not opinions. ;)


I'm still trying to figure out how you obtains these values lol.  I think I see it.  You divided 1V into the total segment, and gives voltage proportional to the length of the measurement. 

I have to agree with WW that the value at V2 is .4V .  We'll ignore all polarities. 

My answer is

V1 = .25V
V2 = .4V
V3 = .25V



   

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It's not as complicated as it may seem...
My answer is

V1 = .25V
V2 = .4V
V3 = .25V

 :D
LOL
   

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It's not as complicated as it may seem...
Gibbs,

Had you drawn a perfect square, your values would be correct.

What you have there is a 2:1 rectangle.

Explain why you think that the two would produce equal results.
   
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:D
LOL

My opinion is we have a disagreement.  ;D


I based my calculation on the angles from primary rather than length of the secondary.  As shown in the picture below, point 1 and 3 have equal amount of primary area radiate out.  That is both have 1/4 flux.  Each 1/4 flux represent .25V .  At point 2, it's 1/2 flux, which is .5V, but if the resistor takes away .1 or .9V, it's still .4V .  

If you were to measure 123- 4 or 5.  You can use the amount of flux based on its angles.  Point 4 is .125V and point 5 is .166V.  



   

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It's not as complicated as it may seem...
Change your diagram to a square.

Now what do you think the voltages will be?
   
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Change your diagram to a square.

Now what do you think the voltages will be?


The exact same as double squares.  There will be some loss as we get further, but it's basically the same. 
   

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It's not as complicated as it may seem...
So the debate appears to about the two segments of wire; 1-123 and 3-123.

You say that the voltage measured across each will be the same magnitude, while I say they will not. Correct?
   
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So the debate appears to about the two segments of wire; 1-123 and 3-123.

You say that the voltage measured across each will be the same magnitude, while I say they will not. Correct?

yes

   

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Aha!


I agree with Gibbs that they are the same magnitude but I say zero volt drop on the first and third measurements because the resistance of the wire between the two measuring points for each measurement is effectively zero Ohms.

The fact that those sections also have inductance is no matter since there is no actual voltage drop across an inductor. --- I think this is another example of the magnetic field line scenario - where it is said one way to allow for understanding but it isn't that way at all.
>>Edit

The important point is that an induced emf is defined only on a closed path and that we must never consider that the path could be broken down into independent sections, each one being as a partial source of emf, all being in series. Nature doesn't work this way.


I agree with Ex on his statement and it applies to my 'choice' of choosing zero volts on the first and third measurements.

In fact... the meter circuit must exist decoupled or not. The actual voltage in existence for the first and third measurements will be zero volts. The 'measured' voltage will NOT be zero volts because the attachment of the meter circuit changes the area of the measured loop.

Yes, I understand these things but tend to jump from actual vs. measured so much I confuse myself.

 
When I said change my opinion to .4V I was referring to the second value, not all three.

Gibbs,

.99 has a good point ( :D). But I see how the area of the loop is a concern while I understand the area of the flux within the loop is the important factor.


All very interesting  :)

--

What a refresher from today! I just spent the entire day on the roof of my house.

Hehehe  .... That reminds me.... When I was a kid I worked as a roofer to put myself through school. The boss fired me because he said I wasn't smart enough to be a roofer. So, I took engineering jobs after that  ;D


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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It's not as complicated as it may seem...
Well,

I got out the rig again and built/tested Gibbs' rectangular loop.

Gibbs & WaveWatcher, you are incorrect with your assertion that both measurements are equal; they are not. WaveWatcher you are incorrect as neither measurement is 0V (you really need to get past that silly notion of yours ;) ).

However, I was not correct either, and now seeing what it actually is, it does makes sense.

Measurement V3-V123 is precisely 1/2 the voltage of V1-V123.

Possible explanation: The V3-V123 measurement has the same amount of flux, but through twice the surface area compared to the V1-V123 measurement?
   

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It's not as complicated as it may seem...
I'll measure and post all the actual voltages from my experiment in the next day or two.
   
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