This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 | Archive 4 | Archive 5 |
Someone the other day claimed that an original research article published in 2006 was not original research because it was published in a reputable journal.
So where do we draw the line? If Prof. AKT Assis publishes something in a reputable journal in 1992 does that then become acceptable mainstream theory? Prof. Assis has shown, based on the electromagnetic theories of Weber, that magnetism is a velocity dependent extension to Coulomb's law. Should we mention that in the introduction? Here is the citation http://www.ifi.unicamp.br/%7Eassis/Commun-Theor-Phys-V18-p475-478(1992).pdf ( 217.44.98.235 10:24, 18 July 2007 (UTC))
The article does mention "lines of force" four times, so I don't see what you're going on and on about, 235. Pfalstad 13:31, 18 July 2007 (UTC)
72.64.45.198 21:19, 18 July 2007 (UTC)
Mr. 235 says, in the portion of the talk page which is now archived: "Why not take a leaf out of the mainstream encyclopaediae and drop the controversy altogether, or at least relegate it to the relativity section." It is relegated to the relativity section! Pfalstad 14:07, 18 July 2007 (UTC)
FyzixFighter, Grant and Phillips derives Ampère's circuital law by beginning with a closed electric circuit. Besides, the div of a curl is always zero and Hence Ampère's law can only hold for closed circuits.
If you want to argue that Maxwell's displacement current is not real, then you needn't also try to tell me that modern textbooks are interpreting Maxwell correctly, and that I am interpreteing Maxwell wrongly.
Once again, I think you are in denial of the higher picture of interlocking solenoidal loops.
Find me a moving charge that is not somehow part of a closed electric circuit.
What is wrong with simply writing in the introduction that magnetic fields are solenoidal lines of force that are found in the region surrounding bar magnets, electric currents and moving charges? ( 217.44.98.235 11:13, 19 July 2007 (UTC))
Hey. I am still looking for that proof from you that "magnetism is a relativistic effect". So far nothing. You giving up? 72.64.48.88 18:38, 18 July 2007 (UTC)
This is very interesting but not relevant to the claim that: magnetism is a relativistic effect. Show me where this statement appears in the books and what the statement purports to mean with respect to an understanding of magnetism. My second edition of Jackson's Classical Electrodynamics page 578 states that it is impossible to attempt "to derive magnetic fields and even Maxwell's equations from Coulomb's law of electrostatics and the kinematics of special relativity." Perhaps this has changed, but the main point here is that the exact meaning of the assertion is unclear and that makes it unsuitable for inclusion in the article on magnetic fields. 72.64.45.198 21:19, 18 July 2007 (UTC)
Agreed. Mention it in the relativity section by all means. But bear at the back of your mind for your own good, that the fraud lies in the bit where they convert the charge term in Coulomb's law into an electric current term. Likewise with Purcell's version too, only he uses a different and contradictory fraud to bring about this same result. ( 217.44.98.235 22:51, 18 July 2007 (UTC))
Pfalstad, you may be right on that point. However, I simply don't know enough about the solar wind to be able to see the full picture. I don't know for sure what exactly it is, or where it goes to.
There is no theoretical reason why we can't have a single moving charged particle, and I would certainly expect such a charged particle to be surrounded by concentric solenoidal magnetic field lines, possibly tapered backwards in a cone.
However, in practice, most situations involving moving charged particles are within the context of closed electric circuits or bar magnets, and it is within that context that the laws of magnetism are formulated.
I myself once mentioned lightning as being a possible case of a broken electric circuit, but that then brings us to the subject of Maxwell's displacement current and whether or not magnetic fields can be broken. It's hardly likely that a solenoidal magnetic field can be broken. Displacement current, whether real or not, ensures that a magnetic field is not broken. Displacement current effectively completes an electric circuit whether it is real or not.
I'm not going to change the present wording in the introduction because it is basically correct. I'm merely drawing attention to the fact that there are reasonable grounds to believe that the full picture of the magnetic field really needs to be viewed within the context of closed electric circuits and interlocking solenoidal loops of magnetic lines of force, rather than in relation to single moving charged particles. Single moving charged particles only give a fragment of the overall picture. I think alot of this argument began because there had been attempts to eclipse the broader picture and focus on the single moving charge scenario.
If the solar wind does spread out radially and indefinitely, is raises rather interesting questions regarding the shape of the solenoidal magnetic field lines that are associated with it.
In fact, on thinking about it for a few hours, it is possible that the solar wind might actually be the one case of an open radial electric current. If the radial symmetry is perfect, I doubt if it could have a magnetic field at all. But in all probability, the symmetry will not be perfect and there will be an axis around which the magnetic solenoidal field loops can form. This would be a case of the magnetic field forming on an ongoing basis at the leading edge of the solar wind. ( 217.44.98.235 10:23, 20 July 2007 (UTC))
Pfalstad, to the best of my knowledge, all materials are either paramagnetic or diamagnetic to a greater or lesser degree. Your latest wording implies that only some are.
The bits that you deleted were indeed superfluous to requirements because magnetism goes back long before Faraday, and Maxwell's equations are more suited to the 'electromagnetism' article, although perhaps a delegation to 'Maxwell's Equations' could be added to those other links.
However, the paragraph below still ignores paramagnetic and diamagnetic force and gives the impression that vXB is the only magnetic force. It ought to be removed and a new section opened up on the Lorentz force in its entirety (E = -gradΦ -(partial)dA/dt +vXB), although even that doesn't cover paramagnetism or diamagnetism, which Maxwell explained using centrifugal force.
Mainstream encyclopaedie tend to give an introduction in a similar vain to the existing one, including references to units. They then tend to follow on with an extra point of interest for example, that a magnetic field surrounds the Earth and that it has been useful to mariners for navigational purposes.
I'm sorry however that you felt the need to pander to the elements that oppose the term 'Lines of Force'. It is a pretty well known mainstream term and depicts the concept very well.It was good enough for Faraday. ( 217.44.98.235 10:48, 21 July 2007 (UTC))
Why don't we put this small deduction of the first equation of the page?
In no-where in a lot of articles have deductions of some simple equations like that, just as "Take this, if you dont understand, sorry, it's not my problem"
I don't think so. biot-savart equation is valid for a moving point charge, because this is the definition of current, charge moving.
This equation Is valid, because In the deduction I never considered independent of
Since the field is conservative, I can sum (integrate) all possible results.
What i'm doing is the same as deduction quatum equations from semi-classic view. they are good approximations for the real case.
And dont forget that Maxwell Equation is only an Approximation for the real word, just like all equations in physics. —The preceding unsigned comment was added by 201.58.7.211 ( talk) 11:44, August 22, 2007 (UTC)
er... er... Deart everybody.
someone said that the equation B = v E K is just valid for low velocities, and for a unique point chage moving. But... Look at my first equation, i use Integrals, since the total MAgnetic field is numerically equal to the sum of infinitessimal.
is non-sense talk about Relativity here.
The maxwell equations is not valid for Eletromagnetism + relativity.
In Relativity, there is no force called Gravitational Force, it is just a inertial force. so we can study relativity without talk about gravitation.
is just as quantum physics, there is no need to know the velocity or position of a particle, but people dont understand it and need help from heisenberg...
we work with newtonian mechanich without maxwell or einsten.
we word maxwell without einstein!!
the relativistic formulaes for eletromagnetismos we leave for relativity, not MAXWELL.
my derivation is complete and beautiful and is not wrong.
give a good argument and dont say non-sense, please —Preceding unsigned comment added by 201.58.7.37 ( talk) 10:17, August 25, 2007 (UTC)
why consider high speed? you are a street racer?
the drift speed of the electrons is very very low! some meters per hour!
the charge is quasi-statical.
i dont know why all this fuzz..
if the equation is wrong, or not "correcT" just delete if from the begin of the article.
i just dont know why put a equation, if the derivation and consequently, the proper equation, is not general, if put the equation, put the deduction! just simple as wind —Preceding unsigned comment added by 201.58.21.236 ( talk) 14:53, August 25, 2007 (UTC)
Hi. I can see this is a contentious issue, but nevertheless I want to challenge the view that the term magnetic field means the B-field (except historically and for those out-of-date engineers). However, I'm not going to claim that it necessarily signifies the H-field either, so put down your weapons. A magnetic field is a physical phenomenon; the influence of one moving charge on another moving charge. The field can be quantified in two different ways; by the force on the second the charge (the B-field), or by the motion of the first (the H-field). OK; that explanation could do with a little work, but you get my drift, and it squares with the physicist who is quoted as saying that the pion trajectories are curved by the "magnetic field" (by the "B-field" would be a poor answer, as that's more-or-less the definition of B). -- catslash 01:43, 7 September 2007 (UTC)
Please can someone check the formula for the strength of the B-field around a wire conductor. I think it should just be "r" and not r-squared on the bottom. We already have r-hat as a unit vector on the top line. It's a while since I did my physics undergrad, and I don't have my textbooks to hand. Please check and verify before changing. 130.138.227.40 15:36, 12 September 2007 (UTC) Andrew (www.techmind.org)
Main article doesnt seem to have the formula for B near a straight wire. Perhaps it should; and similar formulae eg the force between parallel wires. Of all the related electromagnetism articles this seems the most appropriate for people to look for these formulae in. Or is there a better place ? Rod57 ( talk) 05:13, 30 August 2008 (UTC)
The statement in the introduction Unlike the electric field, the force exerted by a magnetic field does no work., surprised me at first. On reflection, I think it's saying that for a moving charge, the acceleration is perpendicular to the velocity. But surely a magnetic field can do work on a magnetic dipole can't it? If so, then this statement should be moved to the Force on a charged particle section, and some explanation added. -- catslash 20:47, 21 September 2007 (UTC)
can anybody tell about MFM used in MO Media? 194.94.133.193 13:02, 5 November 2007 (UTC)
I have thought for a while that the electromagnetism template is too long. I feel it gives a better overview of the subject if all of the main topics can be seen together. I created a new template and gave an explanation on the old (i.e. current) template talk page, however I don't think many people are watching that page.
I have modified this article to demonstrate the new template and I would appreciate people's thoughts on it: constructive criticism, arguments for or against the change, suggestions for different layouts, etc.
To see an example of a similar template style, check out Template:Thermodynamic_equations. This example expands the sublist associated with the main topic article currently being viewed, then has a separate template for each main topic once you are viewing articles within that topic. My personal preference (at least for electromagnetism) would be to remain with just one template and expand the main topic sublist for all articles associated with that topic.-- DJIndica 16:43, 6 November 2007 (UTC)
I really like a lot of the ongoing changes about magnetic field lines, but I'm a bit mystified by the following quote:
As best as I can tell, this is saying something like "Some people think that when you draw in magnetic field lines, that means that the magnetic field is zero wherever you didn't draw a line. But that's not true, because then the magnetic field wouldn't satisfy Maxwell's equations." Is this accurate? If not, what does it mean? If so, could it be stated more clearly? Thoughts? -- Steve ( talk) 06:19, 13 December 2007 (UTC)
Update: I replaced this passage. Thoughts? -- Steve ( talk) 21:51, 14 December 2007 (UTC)
From Faraday's law of electromagnetic induction we obtain,
where curl A = B. This shows that magnetic and electric phenomenona are already different manifestations of the one electromagnetic field even in the same frame of reference. The electric field can be a force per unit charge with magnetic origins. 202.69.178.230 ( talk) 13:53, 4 March 2008 (UTC)
I have been following the discussion here on Magnetic field and relativity. Consider for instance the statement from the wiki A magnetic force can be considered as simply the relativistic part of an electric force when the latter is seen by a moving observer. I think this is misleading. First of all what is the relativistic part of any thing. The force is purely Electrical in nature in one reference frame; it is a mixture of magnetic force and electric force in another reference frame. When moving from one reference frame to the other both parts of the Force are changed as is the Force. Second, having this statement in the same paragraph as the description of how the fields transform has a tendency of confusing the reader. A charge in its own stationary reference frame does not experience a magnetic Force, but this is due to its zero velocity. The magnetic field is 'not' necessarily zero in that frame. The magnetic force is zero but this due to the zero velocity.) We should either eliminate this sentence or expand it.
Here is a proposal for a new way of organizing this wiki. I am writing it here to: get feedback, to help any one who may be considering fixing this, and as a reminder to myself to how I can restructure this should I get the time later to fix it. (Currently I am working on a wiki for gauge invariance)
TStein ( talk) 16:09, 14 May 2008 (UTC)
In this article, within the paragraphs, some vectors are bolded using math mode and other are bolded using wiki markup. The difference is that the math mode is bigger and, I think, has a different font. Looking at other articles it appears to me that most in-paragraph-variables are not in math mode. To me one should either math mode all variables and inline equations or math mode none of them. My question is:
I am leaning toward the latter. Although the former seems to be much more common.
Second, would it be okay if I create another wiki for B vs H? Magnetic_Field_(B_or_H?) that I can shove most of the B vs H stuff into?
164.58.59.20 ( talk) 17:49, 16 May 2008 (UTC)
(I cannot seem to figure out how and why wikipedia is logging me out or not logging me in hopefully this will take.)
TStein ( talk) 17:52, 16 May 2008 (UTC)
I have made some major reorganizational changes following my above outline and it is posted on my personal wikipedia page. This also includes some extra material as well. In addition, I removed some stuff that I felt was too technical for an overview article such as the equation for the Lorentz Force Law. I am thinking about getting rid of the equations for the Biot-Savart Law as well.
I tried to follow Steve's suggestions above, since on further thought I agree with them. My first thought was to make it more technical and more physics like. Here I am aiming to make it more general with links to the more technical content.
This is still work in progress, but I hope it is enough better to post the way it is.
For instance, there needs to be some sort of description of the H field. This is going to take a lot of thought as I am not quite sure if most textbooks themselves understand what the H field is. Some people seem to use it effectively as an applied magnetic field. Many gloss over the fact that unlike B, the divergence of H is not zero and therefore there is an divergence source in addition to a curl source. The result is strange things like 'demagnetization factors'.
After review from enough people I will commit this change to the magnetic_field article.
Any additional changes will be broken into smaller pieces. (I think I made somewhat of a mistake in doing too much with this one edit. I probably should have done one big change that just reorganized followed by a number of smaller committs. Nothing I can do about that now without doing a lot of work.)
TStein ( talk) 01:19, 18 May 2008 (UTC) —Preceding unsigned comment added by TStein ( talk • contribs) 22:41, 17 May 2008 (UTC)
Wow, that was quick! There's a lot here that I like. Reading through, here are some suggestions that occurred to me. Not meant to be a complete list, and anyone else is welcome to comment too.
Anyway, I'm just one guy, and you're welcome to disagree with and ignore any of those suggestions. Also, I don't know if anyone else will offer feedback, you may want to sit on it a few more days before posting, at your discretion. Also, I tend to prefer big all-at-once changes to a zillion small ones, but maybe that's just my opinion.
Happy editing, kudos, and hope all is well! :-) -- Steve ( talk) 17:03, 19 May 2008 (UTC)
Wow, that was quick! There's a lot here that I like. Reading through, here are some suggestions that occurred to me. Not meant to be a complete list, and anyone else is welcome to comment too.
Anyway, I'm just one guy, and you're welcome to disagree with and ignore any of those suggestions. Also, I don't know if anyone else will offer feedback, you may want to sit on it a few more days before posting, at your discretion. Also, I tend to prefer big all-at-once changes to a zillion small ones, but maybe that's just my opinion.
Happy editing, kudos, and hope all is well! :-) -- Steve ( talk) 17:03, 19 May 2008 (UTC)
This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 | Archive 4 | Archive 5 |
Someone the other day claimed that an original research article published in 2006 was not original research because it was published in a reputable journal.
So where do we draw the line? If Prof. AKT Assis publishes something in a reputable journal in 1992 does that then become acceptable mainstream theory? Prof. Assis has shown, based on the electromagnetic theories of Weber, that magnetism is a velocity dependent extension to Coulomb's law. Should we mention that in the introduction? Here is the citation http://www.ifi.unicamp.br/%7Eassis/Commun-Theor-Phys-V18-p475-478(1992).pdf ( 217.44.98.235 10:24, 18 July 2007 (UTC))
The article does mention "lines of force" four times, so I don't see what you're going on and on about, 235. Pfalstad 13:31, 18 July 2007 (UTC)
72.64.45.198 21:19, 18 July 2007 (UTC)
Mr. 235 says, in the portion of the talk page which is now archived: "Why not take a leaf out of the mainstream encyclopaediae and drop the controversy altogether, or at least relegate it to the relativity section." It is relegated to the relativity section! Pfalstad 14:07, 18 July 2007 (UTC)
FyzixFighter, Grant and Phillips derives Ampère's circuital law by beginning with a closed electric circuit. Besides, the div of a curl is always zero and Hence Ampère's law can only hold for closed circuits.
If you want to argue that Maxwell's displacement current is not real, then you needn't also try to tell me that modern textbooks are interpreting Maxwell correctly, and that I am interpreteing Maxwell wrongly.
Once again, I think you are in denial of the higher picture of interlocking solenoidal loops.
Find me a moving charge that is not somehow part of a closed electric circuit.
What is wrong with simply writing in the introduction that magnetic fields are solenoidal lines of force that are found in the region surrounding bar magnets, electric currents and moving charges? ( 217.44.98.235 11:13, 19 July 2007 (UTC))
Hey. I am still looking for that proof from you that "magnetism is a relativistic effect". So far nothing. You giving up? 72.64.48.88 18:38, 18 July 2007 (UTC)
This is very interesting but not relevant to the claim that: magnetism is a relativistic effect. Show me where this statement appears in the books and what the statement purports to mean with respect to an understanding of magnetism. My second edition of Jackson's Classical Electrodynamics page 578 states that it is impossible to attempt "to derive magnetic fields and even Maxwell's equations from Coulomb's law of electrostatics and the kinematics of special relativity." Perhaps this has changed, but the main point here is that the exact meaning of the assertion is unclear and that makes it unsuitable for inclusion in the article on magnetic fields. 72.64.45.198 21:19, 18 July 2007 (UTC)
Agreed. Mention it in the relativity section by all means. But bear at the back of your mind for your own good, that the fraud lies in the bit where they convert the charge term in Coulomb's law into an electric current term. Likewise with Purcell's version too, only he uses a different and contradictory fraud to bring about this same result. ( 217.44.98.235 22:51, 18 July 2007 (UTC))
Pfalstad, you may be right on that point. However, I simply don't know enough about the solar wind to be able to see the full picture. I don't know for sure what exactly it is, or where it goes to.
There is no theoretical reason why we can't have a single moving charged particle, and I would certainly expect such a charged particle to be surrounded by concentric solenoidal magnetic field lines, possibly tapered backwards in a cone.
However, in practice, most situations involving moving charged particles are within the context of closed electric circuits or bar magnets, and it is within that context that the laws of magnetism are formulated.
I myself once mentioned lightning as being a possible case of a broken electric circuit, but that then brings us to the subject of Maxwell's displacement current and whether or not magnetic fields can be broken. It's hardly likely that a solenoidal magnetic field can be broken. Displacement current, whether real or not, ensures that a magnetic field is not broken. Displacement current effectively completes an electric circuit whether it is real or not.
I'm not going to change the present wording in the introduction because it is basically correct. I'm merely drawing attention to the fact that there are reasonable grounds to believe that the full picture of the magnetic field really needs to be viewed within the context of closed electric circuits and interlocking solenoidal loops of magnetic lines of force, rather than in relation to single moving charged particles. Single moving charged particles only give a fragment of the overall picture. I think alot of this argument began because there had been attempts to eclipse the broader picture and focus on the single moving charge scenario.
If the solar wind does spread out radially and indefinitely, is raises rather interesting questions regarding the shape of the solenoidal magnetic field lines that are associated with it.
In fact, on thinking about it for a few hours, it is possible that the solar wind might actually be the one case of an open radial electric current. If the radial symmetry is perfect, I doubt if it could have a magnetic field at all. But in all probability, the symmetry will not be perfect and there will be an axis around which the magnetic solenoidal field loops can form. This would be a case of the magnetic field forming on an ongoing basis at the leading edge of the solar wind. ( 217.44.98.235 10:23, 20 July 2007 (UTC))
Pfalstad, to the best of my knowledge, all materials are either paramagnetic or diamagnetic to a greater or lesser degree. Your latest wording implies that only some are.
The bits that you deleted were indeed superfluous to requirements because magnetism goes back long before Faraday, and Maxwell's equations are more suited to the 'electromagnetism' article, although perhaps a delegation to 'Maxwell's Equations' could be added to those other links.
However, the paragraph below still ignores paramagnetic and diamagnetic force and gives the impression that vXB is the only magnetic force. It ought to be removed and a new section opened up on the Lorentz force in its entirety (E = -gradΦ -(partial)dA/dt +vXB), although even that doesn't cover paramagnetism or diamagnetism, which Maxwell explained using centrifugal force.
Mainstream encyclopaedie tend to give an introduction in a similar vain to the existing one, including references to units. They then tend to follow on with an extra point of interest for example, that a magnetic field surrounds the Earth and that it has been useful to mariners for navigational purposes.
I'm sorry however that you felt the need to pander to the elements that oppose the term 'Lines of Force'. It is a pretty well known mainstream term and depicts the concept very well.It was good enough for Faraday. ( 217.44.98.235 10:48, 21 July 2007 (UTC))
Why don't we put this small deduction of the first equation of the page?
In no-where in a lot of articles have deductions of some simple equations like that, just as "Take this, if you dont understand, sorry, it's not my problem"
I don't think so. biot-savart equation is valid for a moving point charge, because this is the definition of current, charge moving.
This equation Is valid, because In the deduction I never considered independent of
Since the field is conservative, I can sum (integrate) all possible results.
What i'm doing is the same as deduction quatum equations from semi-classic view. they are good approximations for the real case.
And dont forget that Maxwell Equation is only an Approximation for the real word, just like all equations in physics. —The preceding unsigned comment was added by 201.58.7.211 ( talk) 11:44, August 22, 2007 (UTC)
er... er... Deart everybody.
someone said that the equation B = v E K is just valid for low velocities, and for a unique point chage moving. But... Look at my first equation, i use Integrals, since the total MAgnetic field is numerically equal to the sum of infinitessimal.
is non-sense talk about Relativity here.
The maxwell equations is not valid for Eletromagnetism + relativity.
In Relativity, there is no force called Gravitational Force, it is just a inertial force. so we can study relativity without talk about gravitation.
is just as quantum physics, there is no need to know the velocity or position of a particle, but people dont understand it and need help from heisenberg...
we work with newtonian mechanich without maxwell or einsten.
we word maxwell without einstein!!
the relativistic formulaes for eletromagnetismos we leave for relativity, not MAXWELL.
my derivation is complete and beautiful and is not wrong.
give a good argument and dont say non-sense, please —Preceding unsigned comment added by 201.58.7.37 ( talk) 10:17, August 25, 2007 (UTC)
why consider high speed? you are a street racer?
the drift speed of the electrons is very very low! some meters per hour!
the charge is quasi-statical.
i dont know why all this fuzz..
if the equation is wrong, or not "correcT" just delete if from the begin of the article.
i just dont know why put a equation, if the derivation and consequently, the proper equation, is not general, if put the equation, put the deduction! just simple as wind —Preceding unsigned comment added by 201.58.21.236 ( talk) 14:53, August 25, 2007 (UTC)
Hi. I can see this is a contentious issue, but nevertheless I want to challenge the view that the term magnetic field means the B-field (except historically and for those out-of-date engineers). However, I'm not going to claim that it necessarily signifies the H-field either, so put down your weapons. A magnetic field is a physical phenomenon; the influence of one moving charge on another moving charge. The field can be quantified in two different ways; by the force on the second the charge (the B-field), or by the motion of the first (the H-field). OK; that explanation could do with a little work, but you get my drift, and it squares with the physicist who is quoted as saying that the pion trajectories are curved by the "magnetic field" (by the "B-field" would be a poor answer, as that's more-or-less the definition of B). -- catslash 01:43, 7 September 2007 (UTC)
Please can someone check the formula for the strength of the B-field around a wire conductor. I think it should just be "r" and not r-squared on the bottom. We already have r-hat as a unit vector on the top line. It's a while since I did my physics undergrad, and I don't have my textbooks to hand. Please check and verify before changing. 130.138.227.40 15:36, 12 September 2007 (UTC) Andrew (www.techmind.org)
Main article doesnt seem to have the formula for B near a straight wire. Perhaps it should; and similar formulae eg the force between parallel wires. Of all the related electromagnetism articles this seems the most appropriate for people to look for these formulae in. Or is there a better place ? Rod57 ( talk) 05:13, 30 August 2008 (UTC)
The statement in the introduction Unlike the electric field, the force exerted by a magnetic field does no work., surprised me at first. On reflection, I think it's saying that for a moving charge, the acceleration is perpendicular to the velocity. But surely a magnetic field can do work on a magnetic dipole can't it? If so, then this statement should be moved to the Force on a charged particle section, and some explanation added. -- catslash 20:47, 21 September 2007 (UTC)
can anybody tell about MFM used in MO Media? 194.94.133.193 13:02, 5 November 2007 (UTC)
I have thought for a while that the electromagnetism template is too long. I feel it gives a better overview of the subject if all of the main topics can be seen together. I created a new template and gave an explanation on the old (i.e. current) template talk page, however I don't think many people are watching that page.
I have modified this article to demonstrate the new template and I would appreciate people's thoughts on it: constructive criticism, arguments for or against the change, suggestions for different layouts, etc.
To see an example of a similar template style, check out Template:Thermodynamic_equations. This example expands the sublist associated with the main topic article currently being viewed, then has a separate template for each main topic once you are viewing articles within that topic. My personal preference (at least for electromagnetism) would be to remain with just one template and expand the main topic sublist for all articles associated with that topic.-- DJIndica 16:43, 6 November 2007 (UTC)
I really like a lot of the ongoing changes about magnetic field lines, but I'm a bit mystified by the following quote:
As best as I can tell, this is saying something like "Some people think that when you draw in magnetic field lines, that means that the magnetic field is zero wherever you didn't draw a line. But that's not true, because then the magnetic field wouldn't satisfy Maxwell's equations." Is this accurate? If not, what does it mean? If so, could it be stated more clearly? Thoughts? -- Steve ( talk) 06:19, 13 December 2007 (UTC)
Update: I replaced this passage. Thoughts? -- Steve ( talk) 21:51, 14 December 2007 (UTC)
From Faraday's law of electromagnetic induction we obtain,
where curl A = B. This shows that magnetic and electric phenomenona are already different manifestations of the one electromagnetic field even in the same frame of reference. The electric field can be a force per unit charge with magnetic origins. 202.69.178.230 ( talk) 13:53, 4 March 2008 (UTC)
I have been following the discussion here on Magnetic field and relativity. Consider for instance the statement from the wiki A magnetic force can be considered as simply the relativistic part of an electric force when the latter is seen by a moving observer. I think this is misleading. First of all what is the relativistic part of any thing. The force is purely Electrical in nature in one reference frame; it is a mixture of magnetic force and electric force in another reference frame. When moving from one reference frame to the other both parts of the Force are changed as is the Force. Second, having this statement in the same paragraph as the description of how the fields transform has a tendency of confusing the reader. A charge in its own stationary reference frame does not experience a magnetic Force, but this is due to its zero velocity. The magnetic field is 'not' necessarily zero in that frame. The magnetic force is zero but this due to the zero velocity.) We should either eliminate this sentence or expand it.
Here is a proposal for a new way of organizing this wiki. I am writing it here to: get feedback, to help any one who may be considering fixing this, and as a reminder to myself to how I can restructure this should I get the time later to fix it. (Currently I am working on a wiki for gauge invariance)
TStein ( talk) 16:09, 14 May 2008 (UTC)
In this article, within the paragraphs, some vectors are bolded using math mode and other are bolded using wiki markup. The difference is that the math mode is bigger and, I think, has a different font. Looking at other articles it appears to me that most in-paragraph-variables are not in math mode. To me one should either math mode all variables and inline equations or math mode none of them. My question is:
I am leaning toward the latter. Although the former seems to be much more common.
Second, would it be okay if I create another wiki for B vs H? Magnetic_Field_(B_or_H?) that I can shove most of the B vs H stuff into?
164.58.59.20 ( talk) 17:49, 16 May 2008 (UTC)
(I cannot seem to figure out how and why wikipedia is logging me out or not logging me in hopefully this will take.)
TStein ( talk) 17:52, 16 May 2008 (UTC)
I have made some major reorganizational changes following my above outline and it is posted on my personal wikipedia page. This also includes some extra material as well. In addition, I removed some stuff that I felt was too technical for an overview article such as the equation for the Lorentz Force Law. I am thinking about getting rid of the equations for the Biot-Savart Law as well.
I tried to follow Steve's suggestions above, since on further thought I agree with them. My first thought was to make it more technical and more physics like. Here I am aiming to make it more general with links to the more technical content.
This is still work in progress, but I hope it is enough better to post the way it is.
For instance, there needs to be some sort of description of the H field. This is going to take a lot of thought as I am not quite sure if most textbooks themselves understand what the H field is. Some people seem to use it effectively as an applied magnetic field. Many gloss over the fact that unlike B, the divergence of H is not zero and therefore there is an divergence source in addition to a curl source. The result is strange things like 'demagnetization factors'.
After review from enough people I will commit this change to the magnetic_field article.
Any additional changes will be broken into smaller pieces. (I think I made somewhat of a mistake in doing too much with this one edit. I probably should have done one big change that just reorganized followed by a number of smaller committs. Nothing I can do about that now without doing a lot of work.)
TStein ( talk) 01:19, 18 May 2008 (UTC) —Preceding unsigned comment added by TStein ( talk • contribs) 22:41, 17 May 2008 (UTC)
Wow, that was quick! There's a lot here that I like. Reading through, here are some suggestions that occurred to me. Not meant to be a complete list, and anyone else is welcome to comment too.
Anyway, I'm just one guy, and you're welcome to disagree with and ignore any of those suggestions. Also, I don't know if anyone else will offer feedback, you may want to sit on it a few more days before posting, at your discretion. Also, I tend to prefer big all-at-once changes to a zillion small ones, but maybe that's just my opinion.
Happy editing, kudos, and hope all is well! :-) -- Steve ( talk) 17:03, 19 May 2008 (UTC)
Wow, that was quick! There's a lot here that I like. Reading through, here are some suggestions that occurred to me. Not meant to be a complete list, and anyone else is welcome to comment too.
Anyway, I'm just one guy, and you're welcome to disagree with and ignore any of those suggestions. Also, I don't know if anyone else will offer feedback, you may want to sit on it a few more days before posting, at your discretion. Also, I tend to prefer big all-at-once changes to a zillion small ones, but maybe that's just my opinion.
Happy editing, kudos, and hope all is well! :-) -- Steve ( talk) 17:03, 19 May 2008 (UTC)