Kirchhoff is for the birds...

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Author Topic: Kirchhoff is for the birds... (Read 24080 times)

partzman	Re: Kirchhoff is for the birds... « Reply #50 on: 2019-06-27, 15:37:26 »
Group: Experimentalist Hero Member Posts: 1693	Quote from: TinMan on 2019-06-27, 05:50:42 At this point,i would be interested in seeing what a sim says. Is it possible to set the sim up to induce a current through the loop via a toroid as in my setup ?. Brad Brad, Good question? The induction process is normally internal in LtSpice but the electric and magnetic properties of transformer induction can be modeled with gyrator/capacitor networks. I'm just not sure if I'm up to doing that! Poynt? I think a bench replication would be much easier!! Pm

ion	Re: Kirchhoff is for the birds... « Reply #51 on: 2019-06-27, 19:40:50 »
Group: Elite Hero Member Posts: 3537 It's turtles all the way down	FWIW I replicated Brad's toroid induction method this morning on the bench using a Fluke 77 TRMS meter, probing directly across the item of interest I set the input level to the toroid such that I had 75 mV measured across the 1K I then measured 7.5 mV across the 100 Ohm I then measured 82.5 mV across segment A I measured +/-0 mV across segment B 82.5mV total across the resistors minus (82.5mV segment A plus 0 mV segment B) = 0mV KVL holds With segment A looked at as the secondary of a transformer delivering 82.5mV and using the voltage divider rule: Voltage across 100 Ohm = 100/1100 * 82.5mV= 7.5mV Voltage across 1000 Ohm = 1000/1100 * 82.5mV = 75mv Voltage across segment B =+/- 0mV Again using current 82.5mV/1100 Ohms = 75 uA in the loop 75uA * 1000 Ohms = 75mV 75uA * 100 Ohms = 7.5mV « Last Edit: 2019-06-27, 21:36:39 by ion » --------------------------- "Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy

poynt99	Re: Kirchhoff is for the birds... « Reply #52 on: 2019-06-27, 22:41:25 »
Group: Administrator Hero Member Posts: 3217 It's not as complicated as it may seem...	Before I address Brad's post in any detail, I'd like to speak to the question of simulating the Lewin experiment. This immediately leads me to the following question: Can we all agree that both the solenoid and toroid configurations of the experiment can be modeled, and are essentially equivalent to, a loosely-coupled air-core transformer? I did simulate the solenoid configuration years ago, and as with the toroid configuration, would entail using a loosely-coupled air core transformer. There is no easy way that I am aware of to model the B and E fields from a physics perspective. SPICE uses the well-known equations to obtain its results. In order to simulate this experiment in a more realistic manner, I think an electromagnetic simulation tool would be required. However, if all can agree regarding the above question, there really is no need to simulate anything. So let's see what answers arise. --------------------------- "Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe." Frank Zappa

TinMan	Re: Kirchhoff is for the birds... « Reply #53 on: 2019-06-27, 23:14:37 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: ion on 2019-06-27, 19:40:50 FWIW I replicated Brad's toroid induction method this morning on the bench using a Fluke 77 TRMS meter, probing directly across the item of interest I set the input level to the toroid such that I had 75 mV measured across the 1K I then measured 7.5 mV across the 100 Ohm I then measured 82.5 mV across segment A I measured +/-0 mV across segment B 82.5mV total across the resistors minus (82.5mV segment A plus 0 mV segment B) = 0mV KVL holds With segment A looked at as the secondary of a transformer delivering 82.5mV and using the voltage divider rule: Voltage across 100 Ohm = 100/1100 * 82.5mV= 7.5mV Voltage across 1000 Ohm = 1000/1100 * 82.5mV = 75mv Voltage across segment B =+/- 0mV Again using current 82.5mV/1100 Ohms = 75 uA in the loop 75uA * 1000 Ohms = 75mV 75uA * 100 Ohms = 7.5mV So no current flow through segment B Brad --------------------------- Never let your schooling get in the way of your education.

TinMan	Re: Kirchhoff is for the birds... « Reply #54 on: 2019-06-27, 23:19:30 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: poynt99 on 2019-06-27, 22:41:25 Before I address Brad's post in any detail, I'd like to speak to the question of simulating the Lewin experiment. This immediately leads me to the following question: Can we all agree that both the solenoid and toroid configurations of the experiment can be modeled, and are essentially equivalent to, a loosely-coupled air-core transformer? I did simulate the solenoid configuration years ago, and as with the toroid configuration, would entail using a loosely-coupled air core transformer. There is no easy way that I am aware of to model the B and E fields from a physics perspective. SPICE uses the well-known equations to obtain its results. In order to simulate this experiment in a more realistic manner, I think an electromagnetic simulation tool would be required. However, if all can agree regarding the above question, there really is no need to simulate anything. So let's see what answers arise. Well the Lewin experiment is an aircore setup,but the toroid setup contains the B field within the core,and so it would seem not to be an air core setup as such. Brad --------------------------- Never let your schooling get in the way of your education.

ion	Re: Kirchhoff is for the birds... « Reply #55 on: 2019-06-27, 23:24:21 »
Group: Elite Hero Member Posts: 3537 It's turtles all the way down	Quote from: poynt99 on 2019-06-27, 22:41:25 Before I address Brad's post in any detail, I'd like to speak to the question of simulating the Lewin experiment. This immediately leads me to the following question: Can we all agree that both the solenoid and toroid configurations of the experiment can be modeled, and are essentially equivalent to, a loosely-coupled air-core transformer? I did simulate the solenoid configuration years ago, and as with the toroid configuration, would entail using a loosely-coupled air core transformer. There is no easy way that I am aware of to model the B and E fields from a physics perspective. SPICE uses the well-known equations to obtain its results. In order to simulate this experiment in a more realistic manner, I think an electromagnetic simulation tool would be required. However, if all can agree regarding the above question, there really is no need to simulate anything. So let's see what answers arise. I agree with the first part: "Can we all agree that both the solenoid and toroid configurations of the experiment can be modeled" so Yes. Then: "and are essentially equivalent to, a loosely-coupled air-core transformer?" As for the second part it really depends on how you define loose. An air core transformer can be tightly coupled if the construction between primary and secondary is e.g. made coaxially. As you depart from truly coaxial, and spacing between primary and secondary increase, then so does the leakage inductance (uncoupled inductance) and then it can be loose, but that is a matter of degree that we put a number on (the K factor). Of course you already know all this, as you aided my understanding of it regarding Spice simulations. So what number would we be using for the definition of "loose"? And how tightly or loosely coupled can we make the Lewin experiment, provided we want to experiment over a range of coupling factors. Or did I misunderstand the question? Regards « Last Edit: 2019-06-28, 03:09:40 by ion » --------------------------- "Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy

TinMan	Re: Kirchhoff is for the birds... « Reply #56 on: 2019-06-27, 23:47:52 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: poynt99 on 2019-06-27, 22:41:25 Before I address Brad's post in any detail, I'd like to speak to the question of simulating the Lewin experiment. This immediately leads me to the following question: Can we all agree that both the solenoid and toroid configurations of the experiment can be modeled, and are essentially equivalent to, a loosely-coupled air-core transformer? I did simulate the solenoid configuration years ago, and as with the toroid configuration, would entail using a loosely-coupled air core transformer. There is no easy way that I am aware of to model the B and E fields from a physics perspective. SPICE uses the well-known equations to obtain its results. In order to simulate this experiment in a more realistic manner, I think an electromagnetic simulation tool would be required. However, if all can agree regarding the above question, there really is no need to simulate anything. So let's see what answers arise. I would like to add that i !think! you will find that there is no such thing as a loosely-coupled secondary in a toroid transformer. The voltages across the risistors will be the same if the secondary is tightly wound around the toroid as if the secondary loop had a much larger diameter-as in my setup. Although the E field gets weaker the further you go out in the E field radius,you have a higher volume of conductor in the secondary loop. Hope that made sense ?. Brad --------------------------- Never let your schooling get in the way of your education.

ion	Re: Kirchhoff is for the birds... « Reply #57 on: 2019-06-28, 00:15:24 »
Group: Elite Hero Member Posts: 3537 It's turtles all the way down	Quote from: TinMan on 2019-06-27, 23:14:37 So no current flow through segment B Brad Loop current of 75uA through a piece of wire a fraction of an Ohm, this voltage is below the AC resolution of my meter. Lets say the wire was 0.1 Ohm then it would have 7.5uV across it. This is at the level of thermoelectric effects where a slight temperature difference and dissimilar materials can sway the readings. Thus the experiment would have to be carefully constructed if you want to resolve meaningful uV levels. « Last Edit: 2019-06-28, 03:16:24 by ion » --------------------------- "Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy

TinMan	Re: Kirchhoff is for the birds... « Reply #58 on: 2019-06-28, 03:18:27 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: ion on 2019-06-28, 00:15:24 Loop current of 75uA through a piece of wire a fraction of an Ohm, this voltage is below the AC resolution of my meter. Lets say the wire was 0.1 Ohm then it would have 7.5uV across it. This is at the level of thermoelectric effects where a slight temperature difference and dissimilar materials can sway the readings. Thus the experiment would have to be carefully constructed if you want to record accurate uV levels. So an unmeasurable voltage across segment B,but 80+ mV across segment A that has roughly the same resistive value as segment B? Brad --------------------------- Never let your schooling get in the way of your education.

Magluvin	Re: Kirchhoff is for the birds... « Reply #59 on: 2019-06-28, 04:05:44 »
Group: Mad Scientist Hero Member Posts: 546	If the resistors are 1000 ohm and 100 ohm, what is the impedance of the scope or meter? Has it been tested that there really are issues with induction of the test leads? Just askin Mags

poynt99	Re: Kirchhoff is for the birds... « Reply #60 on: 2019-06-28, 04:07:32 »
Group: Administrator Hero Member Posts: 3217 It's not as complicated as it may seem...	Gents, I think the coupling between two closely-spaced coaxial air coils would still be increased by using a core, and I'm not 100% certain but I think a K factor of 1 is almost impossible to achieve with an air-core transformer. On the other hand, it is quite common place to achieve K factors of 0.999 with a soft iron core for example. And I don't disagree about the emf generation; I know the line integral of E along the circumference, whatever it may be, is always the same. Perhaps we could call the toroid configuration a semi-air-core transformer; the primary is tightly coupled to the core, and the secondary is loosely coupled to the core. But I think we are drifting from the point and getting bogged down in unnecessary details. The K factor is irrelevant, and even the core is somewhat irrelevant. The can experiment work with many parameter values. Let me then re-phrase the question such that hopefully we can either simply agree or disagree: Are we in agreement that the Lewin experiment, configured either with a solenoid exciter or toroid exciter, can be simplified and modeled by the attached illustration? ------------------------ Kirchhoff is for the birds... Transformer_Model01.png (6.86 kB, 601x386 - viewed 368 times.) --------------------------- "Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe." Frank Zappa

TinMan	Re: Kirchhoff is for the birds... « Reply #61 on: 2019-06-28, 04:42:06 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: Magluvin on 2019-06-28, 04:05:44 If the resistors are 1000 ohm and 100 ohm, what is the impedance of the scope or meter? Has it been tested that there really are issues with induction of the test leads? Just askin Mags Yes Just put the scope probe through the toroid,clip the earth lead to it,and you have the very same voltage being read from the scope. As i said,the scope is reading the voltage across its own looped circuit. This means it is not reading the voltage across the link that passes through the toroid. Common sense and ohms law both tell us that both conductor links,having the same resistance value,with the same current flowing through them,will have the same voltage across them. One cannot have 80mV+ across it while the other has 0v across it. But it would seem common sense and ohms law is being tossed aside,just so as KVL holds. Despite our differences in other subjects Mags,i know you would search for the actual answer yourself--just as you did with the cap to cap transfer subject,and then again against MH in regards to the ignition system resonance. You stood your ground,and you were correct both times. Perhaps this is another one of those times. Brad --------------------------- Never let your schooling get in the way of your education.

TinMan	Re: Kirchhoff is for the birds... « Reply #62 on: 2019-06-28, 04:59:12 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: poynt99 on 2019-06-28, 04:07:32 Gents, Are we in agreement that the Lewin experiment, configured either with a solenoid exciter or toroid exciter, can be simplified and modeled by the attached illustration? No,as that circuit has only 1 position of measurement,where at least 2 values are needed in order to do any sort of math. Place a 1 ohm resistor inside the hole of the toroid. Then using your measuring method,measure the voltage across that 1 ohm resistor. Now,using ohms law,you will have the value of current flowing through the circuit !apparently!. Once again,using ohms law,you can now calculate the voltage that should be across you other resistor !apparently! So give that a try,and see how things pan out. Brad --------------------------- Never let your schooling get in the way of your education.

poynt99	Re: Kirchhoff is for the birds... « Reply #63 on: 2019-06-28, 05:18:33 »
Group: Administrator Hero Member Posts: 3217 It's not as complicated as it may seem...	Trying to convey information is difficult this way to say the least. If I had 10 minutes with you at a bench, I think it would be a lot easier, and more fruitful. You seem very fixated and aren't willing to or aren't aware of a bigger picture. For instance, why are you so fixated on the notion that the wire segment that is excited can not have a voltage induced (and measured) across it, just because the other wire segment (that is not excited btw) does not? If your logic is limited simply to "because Ohm's law tells me so", then you are choosing to be oblivious to a whole other dimension of knowledge and awareness, which is unfortunate. I can't spend any more time on this when those asking the questions refuse to open their minds. --------------------------- "Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe." Frank Zappa

TinMan	Re: Kirchhoff is for the birds... « Reply #64 on: 2019-06-28, 05:40:52 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: poynt99 on 2019-06-28, 05:18:33 Trying to convey information is difficult this way to say the least. If I had 10 minutes with you at a bench, I think it would be a lot easier, and more fruitful. You seem very fixated and aren't willing to or aren't aware of a bigger picture. For instance, why are you so fixated on the notion that the wire segment that is excited can not have a voltage induced (and measured) across it, just because the other wire segment (that is not excited btw) does not? If your logic is limited simply to "because Ohm's law tells me so", then you are choosing to be oblivious to a whole other dimension of knowledge and awareness, which is unfortunate. I can't spend any more time on this when those asking the questions refuse to open their minds. Poynt It would seem the same applies both ways. I have now posted 3 video's showing the wire segment pasing through the hole of the toroid being well shielded,up to 70% of the complete loop,and the voltage across the load resistor never dropped 1mV,even in my large 3 watt setup. There is no reason to pack up and leave because you think i am not listening,as it would seem to be the same my end,where no one is paying attention to what i am showing--but im still here. And all my tests have shown that the loop is induced via the whole loop,not just the small portion through the loop. If you can explain as to how that very small section of wire passing through the toroid can have a larger voltage across it to that of the opposite link inductor,then i will listen to what you have to say. I am also waiting for your answers on my post a few posts back,regarding Matts comment on the B field-and such. So yes,i would like to know why ohms law dose not work in this circuit. Brad --------------------------- Never let your schooling get in the way of your education.

poynt99	Re: Kirchhoff is for the birds... « Reply #65 on: 2019-06-28, 06:53:29 »
Group: Administrator Hero Member Posts: 3217 It's not as complicated as it may seem...	Let me leave you with one last bit of information that you may wish to contemplate. - Don't confuse (as Lewin does) the resulting E field (from the uniform B field) with the induced emf. They are different animals, and is one of the reasons Lewin's lecture is erroneous. - The resulting E field is non-conservative, meaning it does not equal 0 when traveling the entire loop. No one disagrees with this. - The circular E field is evenly distributed around the circumference if the path has uniform resistance. - A circular wire path with two resistors causes the E field to bunch or concentrate at the nodes of least charge carriers, i.e. the resistor terminals. The E field induces emf's in the adjacent wire segments (solenoid configuration). - There is no E field across an inductor (hence why when the measuring probes are across the wire segments and in the same plane, the measurement is 0V (solenoid config)). - The E field causes an induced emf in the material with the most charge carriers, i.e. the excited wire segment(s). - The total induced emf is equal to, but opposite polarity to the total E field. - Current in a closed loop can not exist without a source of emf. - Current does not just appear out of nowhere. - Current in the loop, either the toroid or solenoid configs, is a result of the induced emf. - The induced emf(s) in a conductive loop (or segments of) is measurable. - The E field distribution and resistor voltage drops due to the induced emf current are equal. - The solenoid config is eloquent, in that it is uniform in all ways and symmetrical. All conductive material produces an induced emf (the vast majority being in the wire segments). - The toroid config is non-uniform, and asymmetrical. The emf is induced in the one wire segment that threads the toroid. - The E field in the toroid config is limited to the area near the excited wire segment, and mostly on the inner side of the toroid. - The E field around the toroid itself is circular and uniform, but from the perspective of one side of the hole to the other side of the hole (the path the loop wire travels), the E field is concentrated and presents an influence to the charge carriers in the wire segment running through its centre. This is what induces the source of emf in that wire segment for the loop current. - With the solenoid configuration, care must be taken when measuring the 4 voltages. In the horizontal plane, all the measurements are of the E field only, and are therefore non-conservative (KVL does not apply, nor do we try to make it so). With the leads in the vertical plane, all the measurements are of the induced emf(s), and resistor voltage drops due to the induced current. These measurements are conservative, i.e. KVL applies and holds. - In the toroid configuration, all the measurements are of the emf, and resistor voltage drops due to the induced emf. It is only if the measurement lead is fed through the toroid centre that the measurement of this wire segment is of the E field only, and since an inductance can not have an E field across it, 0V will be measured. - The voltage must be measured without threading the lead through the toroid, otherwise only the E field will be measured for that wire segment, and KVL does not apply to E fields alone (and we don't try to make it so). It must include the induced emf(s) as well. --------------------------- "Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe." Frank Zappa

TinMan	Re: Kirchhoff is for the birds... « Reply #66 on: 2019-06-28, 10:59:02 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: poynt99 on 2019-06-28, 06:53:29 Let me leave you with one last bit of information that you may wish to contemplate. Quote - The resulting E field is non-conservative, meaning it does not equal 0 when traveling the entire loop. No one disagrees with this. Quote - The circular E field is evenly distributed around the circumference if the path has uniform resistance. - A circular wire path with two resistors causes the E field to bunch or concentrate at the nodes of least charge carriers, i.e. the resistor terminals. The E field induces emf's in the adjacent wire segments (solenoid configuration). I agree,as i stated this in a previous post. Quote - There is no E field across an inductor (hence why when the measuring probes are across the wire segments and in the same plane, the measurement is 0V (solenoid config)). I agree with this as well,as the E field would be around the inductor,on the same plane as the windings. Quote - The E field causes an induced emf in the material with the most charge carriers, i.e. the excited wire segment(s). - The total induced emf is equal to, but opposite polarity to the total E field. I would say no. If we look at a transformer where the B field of the primary induces current flow in a loaded secondary,then that secondary's magnetic field will appose that of the primary. Oddly enough,the two fields have to be of the same polarity (E.G,N and N)to appose each other. I would say the same applies when the secondary is induced via the E field,and there polarities will be the same and in phase. Quote - Current in a closed loop can not exist without a source of emf. In every day stuff like we do,then i agree. But if a magnet is placed on top of a toroid ring,and then that toroid ring is cryocooled to a super conductive state,and then the magnet is removed,then a current will continue to flow around that toroid for as long as it remains in a super conductive state. Quote - Current in the loop, either the toroid or solenoid configs, is a result of the induced emf. I some what agree. But F6FLT had a more accurate description. Quote - The induced emf(s) in a conductive loop (or segments of) is measurable. Yes,except for the example i gave above,regarding the superconductive ring. Quote - The E field distribution and resistor voltage drops due to the induced emf current are equal. I agree that the E field distribution is equal ,but the voltage drops across different value resistors will not be equal. Quote - The solenoid config is eloquent, in that it is uniform in all ways and symmetrical. All conductive material produces an induced emf (the vast majority being in the wire segments). Agreed. Quote - The toroid config is non-uniform, and asymmetrical. The emf is induced in the one wire segment that threads the toroid. Certainly do not agree with that. See video below. Quote - The E field in the toroid config is limited to the area near the excited wire segment, and mostly on the inner side of the toroid. I don't agree with that either. Quote - The E field around the toroid itself is circular and uniform, but from the perspective of one side of the hole to the other side of the hole (the path the loop wire travels), the E field is concentrated and presents an influence to the charge carriers in the wire segment running through its centre. This is what induces the source of emf in that wire segment for the loop current. Nor do i agree with that. See video below. Quote - With the solenoid configuration, care must be taken when measuring the 4 voltages. In the horizontal plane, all the measurements are of the E field only, and are therefore non-conservative (KVL does not apply, nor do we try to make it so). With the leads in the vertical plane, all the measurements are of the induced emf(s), and resistor voltage drops due to the induced current. These measurements are conservative, i.e. KVL applies and holds. Not to sure on this one yet.' I will wait until i have tested my new setup this weekend before i agree. Quote - In the toroid configuration, all the measurements are of the emf, and resistor voltage drops due to the induced emf. It is only if the measurement lead is fed through the toroid centre that the measurement of this wire segment is of the E field only, and since an inductance can not have an E field across it, 0V will be measured. - The voltage must be measured without threading the lead through the toroid, otherwise only the E field will be measured for that wire segment, and KVL does not apply to E fields alone (and we don't try to make it so). It must include the induced emf(s) as well. Ok,KVL only holds if the voltage around the loop equal 0. I have also measured the voltage across the conductor that threads the toroid via the differential method. This means that the measuring lead was not also threaded through the toroid. The voltage value was exactly the same as that of the other resistors link. So as i understand it,you agree that the voltages around the actual loop do not sum to zero. In order for it to sum to 0,we have to subtract the total induced EMF from the sumed voltage around the loop. This makes no sense at all,nor is it right. https://www.youtube.com/watch?v=cqXC7Qjrh1Y Brad --------------------------- Never let your schooling get in the way of your education.

TinMan	Re: Kirchhoff is for the birds... « Reply #67 on: 2019-06-28, 14:22:21 »
Group: Elite Experimentalist Hero Member Posts: 4684	Here is my latest test,where i shield the portion of the conductor passing through the center of the toroid by means of using coax cable,where the outer braid is also grounded. This and my other 3 tests confirm that the induction of the secondary loop is not limited to the small portion of the conductor passing through the toroid. https://www.youtube.com/watch?v=ozngW0DMp30 Plus my previous 3 tests https://www.youtube.com/watch?v=UkUNZ5ik4go https://www.youtube.com/watch?v=n84bPUWLLLY https://www.youtube.com/watch?v=cqXC7Qjrh1Y Brad --------------------------- Never let your schooling get in the way of your education.

partzman	Re: Kirchhoff is for the birds... « Reply #68 on: 2019-06-28, 14:35:05 »
Group: Experimentalist Hero Member Posts: 1693	Brad, FWIW, here is a sim of a toroid driven current loop including an approximate equivalent circuit of the transformer. The calculations show an agreement with ION and Poynt. IMO, the key to realize is that the secondary L2 that passes thru the core will always have a finite amount of inductance and in this case is 10uH. This inductance from A to D therefore has an induced EMF from the primary and is the source voltage for the remaining parts of the loop. The simulation supports this and clearly shows that KVL holds true here. Regards, Pm ------------------------ Kirchhoff is for the birds... Toroid current loop1.png (34.02 kB, 1095x760 - viewed 338 times.) Kirchhoff is for the birds... Toroid current loop1 Calcs.png (14.95 kB, 726x325 - viewed 316 times.)

TinMan	Re: Kirchhoff is for the birds... « Reply #69 on: 2019-06-28, 14:56:08 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: partzman on 2019-06-28, 14:35:05 Brad, FWIW, here is a sim of a toroid driven current loop including an approximate equivalent circuit of the transformer. The calculations show an agreement with ION and Poynt. IMO, the key to realize is that the secondary L2 that passes thru the core will always have a finite amount of inductance and in this case is 10uH. This inductance from A to D therefore has an induced EMF from the primary and is the source voltage for the remaining parts of the loop. The simulation supports this and clearly shows that KVL holds true here. Regards, Pm In my previous post,i show 4 video's of actual tests that say that is not correct. Watch the first in the list at least. It was the one i made just a couple of hours ago. As a sim is based around !what they think! is known,then would you expect it to give any other result?. Brad --------------------------- Never let your schooling get in the way of your education.

ion	Re: Kirchhoff is for the birds... « Reply #70 on: 2019-06-28, 15:18:42 »
Group: Elite Hero Member Posts: 3537 It's turtles all the way down	Quote from: poynt99 on 2019-06-28, 04:07:32 Gents, I think the coupling between two closely-spaced coaxial air coils would still be increased by using a core, and I'm not 100% certain but I think a K factor of 1 is almost impossible to achieve with an air-core transformer. On the other hand, it is quite common place to achieve K factors of 0.999 with a soft iron core for example. And I don't disagree about the emf generation; I know the line integral of E along the circumference, whatever it may be, is always the same. Perhaps we could call the toroid configuration a semi-air-core transformer; the primary is tightly coupled to the core, and the secondary is loosely coupled to the core. But I think we are drifting from the point and getting bogged down in unnecessary details. The K factor is irrelevant, and even the core is somewhat irrelevant. The can experiment work with many parameter values. Let me then re-phrase the question such that hopefully we can either simply agree or disagree: Are we in agreement that the Lewin experiment, configured either with a solenoid exciter or toroid exciter, can be simplified and modeled by the attached illustration? Agreed , sorry if I confused the issue by bringing up the coupling coefficient. --------------------------- "Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy

poynt99	Re: Kirchhoff is for the birds... « Reply #71 on: 2019-06-28, 15:32:04 »
Group: Administrator Hero Member Posts: 3217 It's not as complicated as it may seem...	No worries Ernie, and no mal intent. Just wanted to keep things focused. --------------------------- "Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe." Frank Zappa

ion	Re: Kirchhoff is for the birds... « Reply #72 on: 2019-06-28, 15:42:00 »
Group: Elite Hero Member Posts: 3537 It's turtles all the way down	Quote from: TinMan on 2019-06-28, 03:18:27 So an unmeasurable voltage across segment B,but 80+ mV across segment A that has roughly the same resistive value as segment B? Brad Correct, segment B has no induced EMF in the toroid model. Segment B's fractional resistance value alone determines the voltage measured across it. Quite different than the induced segment A. You need to wrap your head around the fact that transformer induction continues to work on segment A even if it's resistance is close to zero or even a superconductor. drawing attached, can you identify segment A and segment B? ------------------------ Kirchhoff is for the birds... Another view.png (2.23 kB, 317x104 - viewed 304 times.) --------------------------- "Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy

partzman	Re: Kirchhoff is for the birds... « Reply #73 on: 2019-06-28, 15:45:42 »
Group: Experimentalist Hero Member Posts: 1693	Quote from: TinMan on 2019-06-28, 14:56:08 In my previous post,i show 4 video's of actual tests that say that is not correct. Watch the first in the list at least. It was the one i made just a couple of hours ago. As a sim is based around !what they think! is known,then would you expect it to give any other result?. Brad Brad, IMO, your 1st video above does not prove that no induction is occurring in the wire in the center of the coax. There is no shielding action from the outer shield on the coax and in fact, what you now have are two secondaries. The inner wire or 1st secondary, is loaded with the resistor loop and the 2nd secondary or the coax shield, is open circuit and in the same phase. If you place a scope probe on the un-grounded end of the coax, you will see a voltage that is very close (slightly higher) to the sum of the two resistor voltages. If this is not the case, then I am totally incorrect and everything I stated above is false. I will watch the other videos. Regards, Pm

TinMan	Re: Kirchhoff is for the birds... « Reply #74 on: 2019-06-28, 15:52:49 »
Group: Elite Experimentalist Hero Member Posts: 4684	Quote from: partzman on 2019-06-28, 15:45:42 Brad, IMO, your 1st video above does not prove that no induction is occurring in the wire in the center of the coax. There is no shielding action from the outer shield on the coax and in fact, what you now have are two secondaries. The inner wire or 1st secondary, is loaded with the resistor loop and the 2nd secondary or the coax shield, is open circuit and in the same phase. If you place a scope probe on the un-grounded end of the coax, you will see a voltage that is very close (slightly higher) to the sum of the two resistor voltages. If this is not the case, then I am totally incorrect and everything I stated above is false. I will watch the other videos. Regards, Pm Quote: A Faraday cage is an enclosure made of conductive materials which is capable of blocking external electric fields. In other words, it is a hollow conductor capable of keeping the charge or radiation on the external surface of the cage. Faraday cages are used in a wide range of applications, including protection of electronic devices from electrostatic discharge and external radio frequency interference. A Faraday cage is also known as a Faraday shield. Brad --------------------------- Never let your schooling get in the way of your education.

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