hiya I'm really stuck. Anyways, I'm having hard time putting the following questions into words, but I will try. 1) We have two plates. Plate one posseses charge of magnitude Q and plate 2 charge of magnitude A = -Q. Then we put these two plates paralell to eachother. Since plate 1 has net charge, the charge ( amount of charge possesed by plate is Q ) distributes itself over the entire outer surface. I found two texts on the following subject and both claim different things. A) First one says that if we put two parallel plates , then the entire charge of magnitude Q of plate 1 will shift to the particular surface of the plate that is facing the other plate. Same happens with charge contained by second plate. So total amount of charge responsible for electric field between plates will be Code: Q_total = Q + A B) But other text says that charge on plate 1 will remain distributed over the entire outer surface of the object.If that is indeed the case, then only half of plate's net charge will help to create electric field between the two plates. Same with plate 2 ... only half of charge -Q will help create EF between the plates. So total amount of charge responsible for electric field between plates will be Code: Q_total = Q/2 + A/2 Which of the two versions is correct? 2) We have two plates. The left plate ( plate_1 ) posseses positive charge of magnitude Q and the right plate ( plate_2 ) has negative charge of magnitude A = -Q. Then we put these two plates paralell to eachother. EF is created between the plates. If we put a metal plate between the two plates, then metal will become polarised. Metal plate's left surface will have charge of magnitude -Q,and metal plate's right surface will have charge of magnitude Q To my question. Why is excess of negative charge on metal plate's left surface equal to -Q? Why not equal to ( -Q + 1 ) or some other value? Why doesn't EF created by plate_1 attrack more electrons to the metal plate's surface?It's as if each charge in plate_1 is only capable of attracking one electron to the left surface of metal plate?! If I have single proton in space, and 3 electrons near it then this proton will be able to attrack all 3 electron. Why couldn't same be true for protons in plate_1? thank you very much
If your proton captures an electron then the charges are equalized and there is no further attraction due to charge for the other two electrons.
But in order for proton to capture electron it has to bring it very close. And if three electrons are same distance away from proton, then I assume it will attrack all three electrons and only when it captures one of them does it stop attracting the other two electrons? Anyways, how can proton stop attracking other electrons once it becomes neutral? It's not like it turns off its positive charge?
ONE PROTON... only attracts one electron... not 3... if you have a plate.. charged positive.. it will form a field on all sides.. if you have a plate and charge it negative,.... it will form a field on all sides.. if you have a plate, and you remove its electrons... thus giving it a positive charge, and you move all the electrons to another plate... then the field WILL mostly exist between the positive plate and the negative plate. but... the positive plate... doesnt really care from where it gets its electrons.. if we have a nuetral ball near the top of the positive plate.. then a small field will exist towards the free loose electrons in the small ball.. even though all the field should go to the negative plate below... the lack of an electron allows the PROTON electric charge to reach out.. any distance to latch on to electrons and pull them in to nuetralise the charge... the negative plate is called Q-.. because its literally negative and opposite in charge to the postive plate Q+... the best thing to do,, is get NIKOLA Teslas book, experiments with alternate currents of high frequency and high potential, given before the institute of electrical engineers,, london 1891 -MT
the electric field... is actually a collection of lines of force.. one proton, gives off one line of force.. one line of flux... thus grabs only one electron.... if there is any excess positive force given off by protons.. no evidense to prove it has ever been found. that i am aware of... -MT
Would it be possible to answer all of my questions, since I feel they are all vital to my understanding? 1)But if electric field stops existing the moment source charge gets ahold of test charge, then why are electric field lines drawn in the following picture Please Register or Log in to view the hidden image! , since obviously positive charge got ahold of negative charge on the left, so according to you all those electric force lines except for one should stop existing? 2)I know gravity is not the same as electric field but with gravity you have for example earth that can pull on many objects, no matter how many there are. So why can object due to gravity pull on lots of objects while charge can only pull on one at the time? 3)In the following picture Please Register or Log in to view the hidden image! you can see electric field created by source charge. So you mean to tell me that the moment source charge gets ahold of opposite test charge its electric field stops existing and now there is only one line of flux existing (while prior to getting ahold of test charge there were lots of lines of flux) and this line keeps pulling on test charge closer and closer to source charge? 4)But what happens if test charge has same kind of charge ( positive ) as source charge? Will the moment it starts pushing test charge away the electric field ceased to exists except of that one line of flux? What if in the meantime negative test charge appears? How will source charge attract it if electric field doesn't exists anymore? 5)Also, if positive source charge starts repeling positive test charge, then you bring close to source charge as many positive source charges as you like and it won't repel them? 6)And how do test charges know that source charge is already pulling one test charge? If they start pulling on it, then due to newton's third law source charge will have to pull back on them, whether it is already pulling on one charge or not. 7)If positive source charge can only pull away one positive test charge, then positive charges residing on surface of charged object wouldn't be able to pull away other positive test charges that approach this object, since they already are pulling away on each other and as you've said they can only pull on one charge at the time. this is sooo confusing
I would suggsest that you are not seeing the entire picture. These lines all close even if you go to virtual infinity and back. But that would take to large of a piece of paper. Please Register or Log in to view the hidden image!
boris16: The first one is correct. I'm assuming these are conducting plates. If you have positive charge on one plate, it will attact the negative charge on the other plate, and vice-versa. Since the charges can't leave the plate surface, they pile up on one side of the plate - the side closest to the other plate. The question of how much charge is "responsible" for the electric field between the plates should be obvious: all of it contributes to the field. The best proof of this uses Gauss's law. But it has to do with the fact that the electric field inside the central plate must be zero. Thus, the charge on the central plate has to arrange itself to completely cancel out the electric field inside it due to the two charged plates to either side. The electrons being attracted are also repelling each other, so that's part of it. Electric field lines don't stop existing. What gave you that idea? Charge can pull on many at a time, too. If you have one positive charge and 100 negative charges, all 100 negative charges will be attracted to the positive. However, any pair of negative charges also repel each other, which is not the case when consider 100 small objects near a large one, gravitationally. No. That is incorrect.
yes.. but it is so much fun... electrical energy, is perhaps the most fundamental... and the most accessable by us,, humans for use in the laboratory... most scienctists have disregarded the importance of electrostatics, in favor of the electromagnetic components, which are easier to study... of always.. everything starts with electrostatic energy, which forms and creates all electromagnetic.. so in my book.. i give electrostatic aspects of any phenomena.. the benefit of the doubt. -MT
Hi boris, Casting my mind way back, Gauss's law is the first thing that comes to mind, and a search on "gauss law flat plates" provides enough links to sort it out. LIke James said, it appears that text A) is correct... at least for large plates (large meaning that the width of the parallel surfaces is many times the distance between the plates). There will be some fringing, ie the field lines near the edge of the plates will bulge outward, and there will be a little charge on the back of the plates, but this can generally be ignored for practical purposes. Read what Mosheh says with caution. He tends to go against the mainstream. I think that he's not actually cognisant of mainstream physics to begin with.
that hurts my feelings... science is not just my life.. it is my religion. and while it is true... i do often think outside the box... i would ask you to find the flaw in anything i have said. if you cannot, then i would ask for an apology. -MT
The matter of whether an electric field line moves coincidently with its charge source is possibly impossible to experimentally test, since an electric field in motion in a time varying way results in a magnetic field. So, there may never be any clever way to verify that a spinning proton possesses spinning electric field lines, or to disprove it. Beginning with Faraday, scientists have noticed and published that a moving magnet may be discovered to have magnetic field lines which are not attached to the magnet and which do not obtain motion from the motion of the source magnet. Google "Cramp & Norgrove" to find specific information on a 1936 experiment showing this. My point is that since the unification of electric and magnetic force, we may be unable to speak of a moving electric field line, since it must be considered as a moving magnetic field line. However, the results of Faraday's, Cramp & Norgrove's, and other's published science experiments prove that magnetic field lines do not move. Box Score: flaws 1. Apologies zero.
Hi CANGAS, There's very little online about Cramp and Norgrove's experiment. It seems rather obscure. (The top hits on Google point to your discussion of the experiment with Tom in the Nature of Length Contraction thread.) The paper itself is not available online, on the web or on online databases. Nor is it at my local University library. It might be online later this year - ieee.org is currently undergoing an archiving project. But from what I can find, it seems that experiment indicated only that the magnetic field does not rotate when the magnet rotates on its North-South axis. It demonstrated nothing about how any other motion of the magnet affects its field.. The most substantial work I could find was another article in an engineering journal by AG Kelly. It's a bit left field, but it performed some follow up experiments which seemed to indicate that even in the case of rotation on the North-South axis, the field does rotate with the magnet. Personally, I don't think it is even meaningful to talk about a field rotating on an axis of symmetry, but I'm no expert on electrodynamics. Edit: I found more information on Wikipedia, under "Faraday Paradox". Take a look. I found another relevant paper, but haven't had time to read it thoroughly yet: The Unipolar Generator: A Demonstration of Special Relativity
Pete: "the magnetic field does not rotate when the magnet rotates on its North-South axis." If your quote were an accurate statement of the experimental result, is that not enough? That in itself proves that the field lines are left behind while the magnet moves. Do you want Elvis to land in his flying saucer and hand you an engraved platinum notarized letter? I am getting weary of giving references only to have people brag about their inability to find or understand them. The unipolar generator, whether in rotational or linear form, is definitely NOT a demonstration of the legitimacy of Special Relativity. It is, on the contrary, a demonstration of absolute motion. When will you consider beginning to think something through for yourself instead of taking a quote from anyone who happens to mumble something that you have premeditatedly chosen to agree with? Tell me, Pete, what do YOU think about Faraday's statements concerning his remarkable discoveries about the relationship of the magnet and the conducting disk. You have consistently given a perfect imitation of someone who knows nothing about a subject but has learned how to find quotations. Tell me what is remarkable or not about Faraday's findings about the magnet and the disk. According to YOUR understanding, or lack of it, of the subject. You need me to tell you where to find the information, and how to interpret it? Then buzz off, pretender; if I need to tell you anything, then you do not understand the subject well enough to have the right to discuss it with me.
I only looked at this thread because I thought the title meant that someone was stuck in an electric field, and was asking for advice on how to escape. "Wow," I thought. "How unimaginably cool is that!??" Instead, I find that it's just a load of geeks talking about re-wiring plugs or something. I'm disappointed, to say the least.
No, it is not. The experiment indicated that the field does not rotate with the magnet when a cylindrical magnet (actually a solenoid) is rotated on its central axis - and that's all. It neither proved that indication, nor indicated anything about the effect other kinds of movement of the solenoid have on its field. It is trivial to show that moving a magnet moves the field. One easy way is to connect a coil of wire to a multimeter, wave a magnet near the coil, and observe the meter reading. Do you have Cramp and Norgrove's article? If you have a print or scanned version, perhaps you could type up the abstract? I'd be interested in reading what their actual conclusions were, rather than any second-hand interpretation. Did you find and read the Keck article? That is what is in dispute. Do you have anything else to support your assertion? If anything, it is a demonstration of absolute rotation. I have read through the Berg and Alley the article I linked to earlier, and there are no obvious errors. What do you think is wrong with their argument? You mean his actual statements in the 1832 articles? I don't feel like ploughing through forty odd pages of scanned pdf, and I don't particularly care about Faraday's statements - I care about the discoveries themselves, and what they actually mean. I suspect that you don't really care what I think, either, but since you asked so nicely... I toyed with a number of explanations, and haven't committed to any of them. Some are easy to eliminate by experiment. Some are given strong question-marks by other experiment reports (including the non-rotating field). Some I'm not willing to spend the time to analyse fully (including Berg and Alley's relativistic explanation). The one that appeals most to me (not that this is a great indicator) is that the induced reverse EMF in the links connecting the disk to the current detector cancel the forward EMF in the disk. This is strongly supported by descriptions of experiments in Keck's paper that demonstrate that no current is generated if the links and detector rotate with the disk. Now, what do YOU think, and why? CANGAS, I'm getting weary of maintaining politeness in the face of your nastiness. If you want to discuss science, please do so without resorting to insults. If you want to engage in a flame-fest, let's retire to the Cesspool.
