Talk:Magnetism/Archive 1

1. January 2010 There is some vandalism here.. —Preceding unsigned comment added by 159.130.64.3 (talk) 10:50, 8 January 2008 (UTC)

Criticisms

from the article: "are iron, some steels, and the naturally occurring mineral lodestone?" Since steel is an alloy of iron, and loadstones contain iron, shouldn't the list of natural magnets be changed to "iron, nickle, and cobalt."

Lodestone contains iron, but only in the same way that salt contains chlorine: it is the particular way it contains iron that makes it magnetic. You could change it, but they're only examples - the only importance is that everyone will know what they are.

"Animal magnetism?" I had placed a mention of those idiotic magnetic "treatment" devices being sold at stores onto this page, and someone has changed it to "animal magnetism." If there is no objection, I'll change it back to "magnetic therapy" -- because is the popular name for this bogus "medical" treatment. -- Modemac

Another criticism: The statement, "The Earth's North Magnetic Pole (currently in the Arctic Ocean, north of Canada) is physically a south pole, as it attracts the north pole of a compass," is an incorrect assumption. The north pointer of a compass is actually a south magnetized pole. That pointer was originally said to be "north facing," and of course only a south magnetic pole will face north in attraction. Somewhere along the way, the term "north facing" became shortened to "north." A magnet pole is now said by most people to be a south pole if the north pointer of a compass points to it, but this is quite obviously incorrect pole naming. Rickoff (talk) 07:12, 30 July 2009 (UTC)

Additionally Aluminum, Copper and water are not "non-magnetic" substances but highly and demonstrably diamagnetic —Preceding unsigned comment added by 198.103.223.51 (talk) 14:18, 8 January 2010 (UTC)

Rickoff -- I don't think you're right about which is the north pole of a bar magnet. I think the article is correct: The "north pole" of a small bar magnet is by definition the north-seeking pole, the one that points towards Canada. I added a citation to a physics textbook that gives this definition. Do you have some reference that disagrees? --Steve (talk) 18:40, 8 January 2010 (UTC)

Magnetism from electron spin

If magnetism comes from electron spin, why aren't all elements magnetic, as all elements have electrons? At least the ones, that are not full on the outer layer.

Can someone please elaborate on this? THANKS massa 13:50, 10 Jun 2004 (UTC)

I think that all elements that have unpaired electrons are paramagnetic. Ferromagnestism is a different kettle of fish though. ( I don't know enough about ferromagnetism to discuss it) theresa knott 13:54, 10 Jun 2004 (UTC)

Electrons are divided into electron shells of different energies, with the lower energy levels filling up first. There are even numbers of electrons in each shell, and the electrons in each shell are paired to have spins that oppose each other (one is +.5, the other is -.5, every electron having a spin of magnitude one half, either + or -) so that the total spin of any filled shell is zero. That just leaves the last shell; if it is unfilled but has an even number of electrons, the total spin is again zero, no magnetism. If it has an odd number of electrons, there is an extra unpaired spin, which imparts to the whole atom a net spin of + or - .5. These are the paramagnetic elements, which are so weakly magnetic they are not normally thought of in the real world as magnetic, and require laboratory conditions to demonstrate any magnetic effect. (There are obviously many of them, though).

What are normally in the real world thought of as magnetic elements are ferromagnetic metals: iron, cobalt and nickel, atomic numbers 26, 27, 28. With ferromagnetic metals, because the electron shells are large they have several subshells, and the requirement that all electron spins in the last shell except for maybe one odd electron are paired to oppose each other becomes a requirement that all electron spins in each subshell of the last shell except for maybe one odd electron are paired to oppose each other. That's the trick: unlike electron shells the lower energy ones fill up first, the subshells are all in the same shell, and therefore at the same? or similarly close enough? energy levels that there can be several partially filled subshells, and there can be an odd number of electrons in each of these partially filled subshells, and these extra unpaired electrons in the subshells can all have the same spin; so that the total net spin for the atom can be several times + or - .5, therefore that many times the magnetic effect.

Rare earth metals have the same thing happening in the next larger electron shell, with even more subshells, so they can have an even higher total net spin per atom than ferromagnetic metals, which is why they can be used for such powerful magnets. (This is a 30 year old memory of what was at the time a very good physics education, so take it for what it's worth). Gzuckier 16:08, 20 Aug 2004 (UTC)

electron spin has magnitude hbar sqrt(s(s+1))=sqrt(3/4)hbar. s, which is always 1/2 for electrons, is the spin vector. you have the two mixed up. the person who responded second below is correct. Iron is paramagnetic, but it creates a strong bulk magnetic field due to "domains" of aligned spin states. in most paramagnetic materials, all the spins are randomly oriented, and so the BULK magnetic field is small. in Iron, these domains tend to add and create a large BULK field. consider oxygen. oxygen has a triplet ground state (2 unpaired electrons). this fact causes the "poles" to allign, such that a permanent magnet will attract liquid oxygen. however, because oxygen is either a gas or liquid in most situations, the randomness inherent to those phases causes it to have no bulk field. many organic persistent free radicals exist, and are studied for their magnetic properties for use in electronics. Let me mention that you are partially correct, but mostly incorrect about metals. metals DO have orbitals that are close in energy, causing electrons to be distributed among states in a much less standard and structured manner than other elements. this DOES often result in multiplet ground states. however, because fermions are indistinguishable, it is incorrect to say that many of the electrons are all spin up or all spin down, and therefore add to the field by some number times the number of unpaired electrons. once again, the strength of the bulk field is a consequence of the degree of alignment of the spin states among neighboring atoms. it is not a matter of how many unpaired electrons are in an atom. I want to end this by saying that the confusion that is shown in this talk page scares me. the fact that people who have such a misunderstanding of a topic are possibly also authors of the article exemplifies the biggest problem with wikipedia. At the same time, I am glad that I noticed this, because I will certainly never trust wikipedia again. I hope a sysop or other such person reads this, because it is important that they see this first hand.--Gordonliu420 (talk) 03:14, 6 July 2008 (UTC)

only 1 of the rare-earth elements is ferromagnetic. —DÅ‚ugosz 15:34, 8 Apr 2005 (UTC)

That's still paramagnetism - you have a bunch of atoms with spins of several times .5, but the spins all point in random directions so they don't amount to much. In ferromagnetism nearby spins point in the same direction and their effect adds up. (The ferromagnetism article explains this better) Whether or not the spins line up depends on the type of atom(s), but also on arrangement of the atoms. For example, arrange iron in a BCC lattice and it's ferromagnetic, put it in an FCC one and it isn't. 131.203.9.226 08:08, 14 Jun 2005 (UTC)

Electron spin can cause magnetic force, but so can any electron motion, and so can any charge motion. There is much more to the cause of magnetism than electron spin. We probably need to fix this article. John 02:00, 8 August 2007 (UTC)

The magnetic force that occurs on magnet is NOT caused by the electron SPIN. But because of the electron ROTATION. It is a big difference. Remember that electrons are rotating the protons and neutrons inside. It analogues with the magnetic field that produced by a loop with current. When the electrons of atoms rotating at RANDOM direction, the magnetic field total is Zero. Thus, it is not a magnet. But when they rotating at the same direction, it creates magnet. Wisnuops (talk) 15:11, 29 April 2009 (UTC)

Magnetic monopoles

Contrary to normal experience, theoretical physics predicts the existence of Magnetic monopoles.

Is this still true? Do we have any examples of this viewpoint later than 1931? anthony (see warning) 00:18, 20 Aug 2004 (UTC)

Fang et al., The Anomalous Hall Effect and Magnetic Monopoles in Momentum Space, Science 2003 302: 92-95

Jeon, H. and Longo, M. J. "Search for Magnetic Monopoles Trapped in Matter." Phys. Rev. Lett. 75, 1443-1446, 1995.

Gzuckier 16:08, 20 Aug 2004 (UTC)

I really don't feel that the theoretical justifications are accepted well enough in the physics community to be considered certain. I mean, in my Electricity and Magnetism class part of one of the lectures showed how magnetic monopoles led to a contradiction, and magnetic monopoles have not been shown to exist experimentally. This section on magnetic monopoles should probably mention how conventional electromagnetic theory holds that magnetic monopoles are impossible. Robotbeat 09:51, 20 November 2005 (UTC)

Many have forgotten that in 1905 Einstein explained the fundamental cause of magnetism; the relativistic forces between moving charged bodies. When we analyze magnetism with an understanding of what causes it, it is abundantly clear that there could be no monopoles. But without an understanding of relativity, and under the misconception that magnetism is a fundamental force, monopoles could appear plausible. John 07:00, 8 January 2007 (UTC)

John, Einstein did not close the book on electromagnetism in 1905; far from it. Since then we've a whole lot more about it, through quantum mechanics, quantum field theory, and finally quantum electrodynamics and gauge theory. We now know, for example, that not all magnetism is caused by moving charge (see spin (physics)). The assertion that monopoles could or should exist has been made in thousands of well-cited papers by leading physicists in the last three decades. Of course, monopoles have never been observed, and but their (extremely rare) existence is consistent with everything in modern and classical physics. Of course, their non-existence is also very possible; the article's description, "some theoretical models of physics predict monopoles", is exactly right. --Steve 13:40, 12 August 2007 (UTC)

Magnetic Attraction

Anyone interested in explaining what is the property by which the two pieces of magnetic material are attracted to each other? For example, is the attractive force in the flux lines, or where? What brings them together? wojmax 27 sep, 04

This is elegantly explained under the monopole section. Perhaps it should replace the lead section? John 07:02, 8 January 2007 (UTC)

Merging of Magnetism and Electromagnetism?

Shouldn't those 2 articles be merged and redirected as un the francophone wikipedia?

Object. Magnetism and Electromagnetism are related topics which were discovered in a historical order. Gilbert built up a theory first (the Earth is a huge magnet). Electricity began to be understood 100 years afterward, with Maxwell unifying the theory 250 years after Gilbert. Further unifications are going on today. Magnetism as a concept is alive and well. Ancheta Wis 21:28, 5 Mar 2005 (UTC)

I agree, there's a history to magnetism. And magnetism is way broader of a topic then Electromagnetism. I think the topic Electromagnetism can be used for more thorough scientific explenations, while the term 'magnetism' is used in the mounth of the average daily life man. I would prefer a more simple to understand topic in magnetism, and a more scientific (with formula's) view on Electromagnetism.

I do however would like to keep the link towards the electromagnetism topic.

Magnetic monopoles: problem sentence

I think there are problems with this sentence: These monopoles, unlike that of elementary particles are solitons, namely localised energy packets. My guess is that it should read: These monopoles, unlike Dirac's elementary particles, are solitons, namely localised energy packets (ie replace "that of" with "Dirac's" and add a comma), but I don't know the subject well enough to be certain. Hv 19:41, 16 July 2005 (UTC)

There is no definition of the term ``posit. This section is too long, wrt the fact a dedicated article exists, and this topic is not really one i consider ok for a general introduction to magnetism.

Magnetic Refrigeration

Is this topic covered as of yet? I couldn't find it anywhere. Thanks.

Yes . Its covered here [1]

Magnetic materials

This shouldn't be covered in an article on magnetism. Someone ought to move this section elsewhere. --Smack (talk) 04:59, 16 November 2005 (UTC)

I agree...In particular, I would strongly suggest the section "Permanent and temporary magnets" be moved to the article on magnets. --Steve 16:56, 18 August 2007 (UTC)

Speed of charged particles

How fast can a charged particle move in a magnetic field?--Light current 03:04, 29 December 2005 (UTC)

A particle in a magnetic field can have any velocity that is less than the speed of light. But it is misleading to think that the velocity of a charge particle is affected by the magnetic field. The magnetic field only changes the direction of the moving particle, not its velocity. In fact if the particle had no velocity there would be no magnetic force exerted on the particle, even in the strongest the magnetic fields. I wish I could go into more detail but if you look at the equation Fmag=q(v) X B, you will see that the charge particle will travel in a circular path perpendicular to the magnetic field. Its tangential velocity will remain constant while in the magnetic field and its radius will be r such that m(v^2)/r=qvBsin(Θ, where m is the mass of the particle.

I know that this question has gone unanswered for quite some time, but it’s a good problem for anyone that wants to learn about vector cross products and force laws. I I hope people will correct me if I have gotten anything wrong in my explanation.

Later -swimguy112 Feb 2007

Hi there.

I do strongly believe that magnetism is not fully understood under the light of our scientific knowledge. We know that the whole Universe is crisscrosed by waves emited by stars. Those waves cover awide range of frecuencies and amplitudes. Some are called visible, others are invisible like x rays, radio waves,ultraviolet,micro waves and electromagnetic waves. The electromagnetic waves account for gravity or gravitational fields. Coulhom "law" is the same "law" that Newton created for gravity. Maybe they confused a single magnetic effect as observed in the case of planets and electric charges. And even mmore, perhaps Eistein was weary of gravity as a force as much as a simple ralation of positive and negative charges.He knew that none could explain the cohesive force in atoms and, rather than arguing with his distinguished colleagues prefered the idea of a weak and strong forces, that is yet to be proven. It is clear that magnets cancel gravity as seen with diamagnetic materials, super diamagnetism, super magnetic fields and a lot of diferent "weird" effects used in so many levitating curiosities. --Dr. E. Camps. (201.242.161.177) 23:57, 1 February 2006 (UTC)

Besides being utterly crackpot, beliefs have no place in a scientific encyclopedia article. What's the point? Femto 12:52, 2 February 2006 (UTC)

Dr E Cramps, your ramblings constitute incomensurate loonery.--feline1 15:03, 2 February 2006 (UTC)

Dr. E. Cramps, I'm sure that you are a very clever person (hence your title) but I'm Sure you didn't get it in the research of magnetic effects. Stick to what your good at.

wahehe, ang galing!

uuhhh... I don't even know where to begin with this one, but from what I can tell you are mixing up your forces. The gravitational, electromagnetic, weak and strong are viewed as separate forces in most applications. There are some similarities between their mathematical equations, the gravitational and coulomb forces for example. But the physical mechanisms that drive these forces are very different. So your statement “electromagnetic waves account for gravity or gravitational fields” is incorrect. Gravitational fields are the result of the curvature of space-time while EM waves are the result of interacting electric and magnetic fields produced by oscillating charged particles. Theoretically EM waves can cause gravitational fields however, this is a very extreme case that i dont believe has been done experimentally. There are other problems with your statement but i wont go into them.

You are right to say that we do not know everything there is to know about magnetism but we know enough to harness it for our everyday purposes... and write a wikipedia article about it.

-swimguy112

Mention Magnetization in the SI unit table?

There is no mention of magnetization in the SI unit table, and little mention of it at all in this page. I'm not qualified to add this kind of info to this page, so I preferred to raise the issue here. I think that this page is rather isolated WRT other magnetism pages... http://en.wikipedia.org/w/index.php?title=Special:Whatlinkshere&target=Magnetization BTW, I've added a "See also" link at the bottom of the magnetic moment page...

Persistence of Permanent Magnets

How long to "permanent" magnets last? What influences their decay?

Good question. What basically drives it is that the molecules wander away from being all lined up in the same direction. From high school experiments, heat and/or pounding with a hammer both contribute to that. (and if you hold an unmagnetized piece of iron in a strong magnetic field, heat and/or pounding will make it magnetic). Otherwise, I don't know, over time the molecules slowly move? Maybe somebody else can further that. Gzuckier 15:26, 16 August 2006 (UTC)

I seem to recall that in magnetic hard drives (a relevent example, since there, decay equals data corruption), each bit is hundreds of grains, and each grain is a single magnetic domain. The magnetization occasionally flips according to an Arrhenius equation; the bigger the grains, the less often they flip. This gets in the way of miniaturization; manufacturers have to keep the grain size big enough that the halflife is about ten years. For materials with more than one domain, I imagine that thermal movement of domain walls is the dominant decay mechanism, but I don't know how that's modeled. But the short answer is: thermal processes randomize magnetization like everything else, and the timescale can probably be anywhere from microseconds to the age of the universe, depending on details of the material. --Steve 04:27, 11 August 2007 (UTC)

Math Parse failure?

When I open the article I get the following message: "Failed to parse (Can't write to or create math output directory): \vec F = q \vec v \times \vec B". Why is this happening?

Magnetic field used as a defensive shield?

Kind of a dumb question, but hypothetically, could a device generate a magnetic field strong enough to repel bullets?

I would think so, as long as they were conductors of electricity. Not repel, but cause the kinetic energy to be converted to electrical energy and get dissipated in internal resistance inside the bullet. Of course then somebody would shoot you with a wooden bullet. Gzuckier 17:18, 31 October 2006 (UTC)

So what would happen to the bullet when it enters the field? Just fall down?

Yeah, I think it would just slow up, if the field was strong enough it would just fall. Gzuckier 13:32, 2 November 2006 (UTC)

Sweet.

Project help

hi ....am sha am doing a project in magnetism..........am having certain doughts regarding inductor.......whenever we design an inductor we will predict its temperature rise above ambient (Theoraticaly)..but in actual case the temperature exceeds our prediction hence it affects the performance of the inductor..which leads to reduce its efficency......i have certain ans regarding this.......but am not compleatly sure about that.......

thank u shah

This talk page is for writing the encyclopedia article, not electrical engineering help, unfortunately. -- Beland 04:19, 1 April 2007 (UTC)

Vandalism on this article

There've been a few incidents of apparent vandalism, or at least unintended nonsense edits, by some people in 209.79.65.x domain. I've reverted the latest, but what I neglected to say in my edit comment was that I reverted to the latest edit by VSmith... Sinewalker 00:58, 16 March 2007 (UTC)

Effect of Magnetism on Strength of Metals

What is the effect of Magnetism on metals such as Iron and steel? Does the presence of magnetism improve the strength of the metal? Does it make it more elasitc? Does it weaken it? Do these changes persist once the magnet is removed from the metal? —The preceding unsigned comment was added by 71.127.246.251 (talk) 14:56, 26 March 2007 (UTC).

magnets

magnets should be seperate article

F=qv*B i don't like the way it's written

it's the first time i partecipate to a discussion in order to modify a page, soi hape to do everything properly. Anyway, i don't agree with the way the formula fo the magnetic force is written, because there is the vectorial product between the two vectors (v and B are separated by a x, which is often used as operator of vectorial product) and there is at the same time the sinus of theta. The sinus should not be there, because it's included in the vectorial product! or, if we prefere not to use the vectorial product, we could include the sinus, but we should show that the two vector are de modulus of the vector, something like F=q|v||B|sinTHETA.

Thanks for your note. I fixed it.Yevgeny Kats 20:23, 21 May 2007 (UTC)

Question

Question: what exactly (on the molecular level) is happening to a material when it is magnetized? - pasted from article by Geologyguy 00:09, 14 June 2007 (UTC) (question is from an anon)

Two Items: Magnetic properties and temp, and the caption for the filings image

One: Recent episode of CSI mentioned 932 degrees Fahreinheit as the temp at which iron magnets lose their magnetic properties. Looked on the page, couldn't find the topic. I'll assume CSI got it wrong, but does this happen, and at what temp, and where would that be on the page and on Wiki? Two: The imagine of filings on paper actually looks like an engraving of filings on paper. Shoud that caption be edited to correctly reflect such? ThuranX 01:46, 16 July 2007 (UTC)

The Curie point of pure iron, at which it loses its magnetization, is listed here as 1043ºK, or 1418º F. Most common (and uncommon) magnets are not pure iron, but are some alloy of iron-nickel and other things. As for the image, of course I don't know for certain, but it looks to me exactly like a photograph of iron filings on paper. Cheers Geologyguy 02:22, 16 July 2007 (UTC)

Maglev Theory

I know a little about the technology of Maglev (ie I have visited the maglev website, read up on it, the concept is simple)

So it raised some questions.

1. Is there are material that can dampen, reflect or contain a magnetic wave? If so, might it be possible to hover something, on a sort of track. Imagine a toboggan run where a sheet of magnet is hovering in a 'U' shaped track.

2. Maglev reports the maximum speed to be around 550km's. Surely it could go much faster than this, what limits the speed?

3. (more of a theory) Imagine you hold a powerful electro magnetic rod, with a contained and directed flow of attraction (Q1) on an angle above an attracting sheet of magnet, then slowly increase the voltage to the magnet, wouldn't it then pull to the point ahead of it?

Where is all this going? Well I had an Idea that you could propel of levitated "base" using a contained electro magnet. If the electromagnet was anchored to the "base" at a certain angle, it may attract to the track in front, thus propelling, and accelerating the base, possibly incredible speeds possible. Especially if the track was setup inside a vacuum.

-nick (13:21 6th August 2007)

1. No because magnetism is not a wave. However superconductors levitate magnets.

2. The limits for speed maglev would be the speed of light.

3. No, it would only pull to the nearest magnetic object, magnetism is not directed the way you need it to be. John 02:11, 8 August 2007 (UTC)

magnetotactic bacteria

This sentence was misplaced in the 'history' section and was removed and preserved here. It is interesting, but needs a better home. ___ In the natural world, magnetotactic bacteria had evolved miniature magnets inside themselves and used them to establish their orientation relative to the Earth's magnetic field [2].

There is no need for this edit removing the section of monopoles. It is a standard application of the widespread practice of Wikipedia:Summary style. Melchoir 07:38, 8 August 2007 (UTC)

Also, some of your other edits[3] are troubling, as they seem to imply a substantive difference between electric current and moving electric charges, which are virtually synonymous and refer to the same physical phenomena. Melchoir 07:43, 8 August 2007 (UTC)

Physics of magnetism

I have some problems with the "Physics of magnetism" section.

"It is a common abstraction to view the cause of magnetism as electric currents. However, our modern understanding of magnetism goes beyond that."

This is a good start -- indeed, our modern understanding includes things like electron spin, which is certainly not an electric current.

"All magnetic effects are actually due to relativistic effects caused by relative motion between the observer and the charged particles." (citing Einstein's special relativity paper)

Even if this was premised, "Classically,...", as it should be (spin is a magnetic effect which doesn't fit that statement), this would still be misleading at best. It reflects the view that electric fields are privileged and natural, and then special relativity implies that magnetic fields must exist too. It's certainly true that electricity without magnetism violates special relativity, but that does not mean that magnetism is a consequence of electricity...you could equally well say that electricity is a necessary consequence of the application of relativity to the phenomenon of magnetism. In reality, E&M are an inseparable bundle, which physicists treat on an equal footing.

I appreciate that electrical attraction and repulsion is something people can sink their teeth into, and feel they viscerally understand, and therefore is attractive as a foundation for the intuitively weirder idea of magnetism. But this is a crutch, and we shouldn't let intuitive attractiveness trump physical and logical correctness.

I suggest something to the effect of "due to the insights of special relativity, electricity and magnetism are inextricably linked. Observers moving at different velocities will measure different charge densities and currents (due to length contraction and time dilation), and hence different electric fields and forces. However, the magnetic fields, particle velocities, and hence magnetic forces, will also change, such that the net force is consistent between the different observers." That's pretty hard-to-read right now, but I think closer to the right idea.

"Maxwell's Equations and the Biot-Savart law describe the origin and behavior of the fields that govern these forces. Therefore magnetism is seen whenever electrically charged particles are in motion. This can arise either from movement of electrons in an electric current, resulting in "electromagnetism", or from the quantum-mechanical spin and orbital motion of electrons, resulting in what are known as "permanent magnets"."

The first two sentences are really only talking about classical E&M. Thus the example of spin in the third sentence doesn't follow from the statement in the second. And the third sentence is just completely inaccurate.

If I get a chance, I'll try to rewrite this section, hopefully without sacrificing comprehensibility. --Steve 04:44, 11 August 2007 (UTC)

Steve,

Your statements are scientifically correct. It has been suggested that the introductory parts of articles like this be readable by people not highly educated in the field. The challenge is to strike a balance between what would be viewed by laymen as esoteric correctness and articulating the basic idea. I encourage your efforts to make this technically correct, but in doing so, please make sure your whole extended family can understand it. Please keep in mind that little people are reading this stuff sometimes too. If you loose the reader in the first section, you don't get him back. Since I can't seem to always be technically correct and elementary at the same time, the way I try to handle this is to make the material early in the article more assessable while not technically wrong. Then deal with the esoteric correctness below. (This may mean reorganization of the article.) John 01:13, 21 August 2007 (UTC)

My comments pertain to the phrase: "..results from the electron's orbital motion about the nucleus." I'm not a physicist, but my understanding was that electrons do not move with classical "orbital motion," which would imply that gravitation is a major factor in the structure of an atom when it is in fact irrelevant. Therefore, I'm removing the offending word: "orbital." But I do not know whether the rest of the statement makes sense without it, so I cannot offer any true fix.--68.36.99.29 (talk) 22:45, 6 June 2008 (UTC)

Hmm, well "orbital" is a term that has a specific meaning in quantum mechanics, which has nothing to do with gravity. But not all readers will know that definition. To help, I'm putting in a Wikilink to orbital angular momentum under the word "orbital". --Steve (talk) 00:46, 7 June 2008 (UTC)

Magnetic Domains

Adding a section describing the action of Magnetic domains in this article would address some of the topics cited as missing now. John 21:20, 28 August 2007 (UTC)

Template:Electromagnetism vs Template:Electromagnetism2

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 16:52, 6 November 2007 (UTC)

Magnetic monopoles revisited

Certainly these exist depending upon the definition. I can deliver as many as you want or you could make them yourself. Just take two permanent magnets and force like poles on each to stay together. This is more easily done if the permanent magnets have a hole through the middle. Then they could be bound mechanically with a screw for instance of glued if the glue's strong enough.

If you've bound the south poles together the resulting piece is a magnetic north monopole.

AdrianAbel (talk) 10:59, 29 April 2008 (UTC)

You can't go around making up your own definition of magnetic monopole. They have a specific technical definition that everyone agrees on, and according to that definition, two glued-together bar magnets is not a magnetic monopole. You might just as well say that "flying saucers exist depending upon the definition", because I can throw a teacup saucer in the air. :-) --Steve (talk) 16:44, 29 April 2008 (UTC)

Magnets glued together like that form a magnetic quadrupole, not a magnetic monopole. Xxanthippe (talk) 22:55, 29 April 2008 (UTC).

Fine. The last sentence of my contribution should have been: ... wouldn't the resulting piece be a magnetic north monopole? I was actually looking for a definition in the article. A definition of a mono or whateverpole is not what something "would be" but what it actually is and can be undisputedly identified as such. Also my contribution clearly states "depending upon definition ..." which I don't offer. A quadrupole is defined in a corresponding article. It also is not what I offered.

AdrianAbel (talk) 17:13, 1 May 2008 (UTC)

Ah, I see. I apologize for my slightly-mean response then. My view is that a reader interested in the precise definition of a magnetic monopole would presumably click the link to the article Magnetic monopole, and read about it there. No need to crowd this general article with too much detail about a niche topic. Hyperlinks are the whole beauty of Wikipedia, IMO. :-) --Steve (talk) 20:58, 1 May 2008 (UTC)

Special relativity doesn't link electricity and magnetism

"As a consequence of Einstein's theory of special relativity, electricity and magnetism are understood to be fundamentally interlinked."

This is in the section which talks about electricity, magnetism, and special relativity, so deleting this doesn't fit well, but it's misleading. Faraday was the first to link the two, and by the time they were used in Maxwell's equations they were clearly understood to be linked. Kestasjk (talk) 15:37, 14 May 2008 (UTC)

Do you acknowledge that magnetism is a relativistic effect of motion between electric charges? John (talk) 01:49, 3 July 2008 (UTC)

For my part, I'd say that Maxwell's equations show that electricity and magnetism are phenomenologically interlinked, while SR shows that they're fundamentally interlinked. But I haven't thought too hard about it. Anyway, I think the sentence works as the topic sentence of that paragraph, even if it's slightly misleading in isolation. --Steve (talk) 02:41, 3 July 2008 (UTC)

Steve, in my view, SR goes a good bit beyond showing they are fundamentally linked, it offers (enables?) a satisfying and sensible explanation of the cause of that linkage (to the extent that SR is itself sensible). John (talk) 03:18, 3 October 2008 (UTC)

Is bringing up spin helpful?

The question is which of the following statements is better in the article:

(1) Every electron, on account of its spin, is a small magnet (see Electron magnetic dipole moment).

versus

(2) Every electron, by its nature, is a small magnet (see Electron magnetic dipole moment).

I put (2) in a while ago, TheBendster turned it to (1), I changed it back, and Xxanthippe changed it back again. Anyway, here's my justification of why (2) is better. A reader who doesn't know anything about magnetism, seeing (2), might have the legitimate question: "What is it about the electron that it has a magnetic moment?" In which case they can click the link and learn all about it. On the other hand, a reader who doesn't know anything about magnetism, seeing (1), would have not one but three legitimate questions: (A) "What is it about the electron that it has a spin?" (B) "What the heck is spin?" (C) "What does spin have to do with magnetic moments?" The very-curious reader is left with three difficult unanswered questions, not just one; while the less-curious reader has two unanswered questions (B and C) instead of zero.

Here's an analogy, which I also put in my recent edit summary. An article referencing the electrons mass could say either

(1') Every electron, on account of its coupling to the Higgs boson, has a mass of 10^-27 grams

versus

(2') Every electron, by its nature, has a mass of 10^-27 grams.

It's true that (1') is more descriptive, in that mass is well-known by physicists to be a derived property, derived from the more fundamental electron-Higgs coupling. But I think it's obvious that (2') is to be preferred in an encyclopedia article.

Any thoughts? Or can I change it back to my preferred (2)? --Steve (talk) 00:52, 8 July 2008 (UTC)

Well, the first motivation for my edit was actually to remove the phrase "by its nature", which (to me at least) comes across as rather condescending (kind of like saying "just accept it - you're not smart enough to understand"). From that point of view, an alternative is just to remove that phrase, just leaving "Every electron acts as a small magnet (see Electron magnetic dipole moment)".

However, there is another problem, which is where we talk about "random orientations" leading to no bulk magnetism. I think that including spin helps make this part more clear, but I could probably be convinced otherwise.

Finally, I would like to point out that there is a large subset of the scientific community who know very little about magnetism but plenty about spin. They're called "chemists", and version (1) is very helpful to them. In the same vein, I have nothing against (1'), and probably even prefer it to (2'). I don't think the additional information confuses or obscures the main subject of the sentence, so I don't see any reason to omit it.

OK, one more semi-developed thought. Maybe saying "angular momentum" instead of "spin" could work. This would have the advantage that the "spin" paragraph and the following paragraph (concerning orbital angular momentum) could be merged. We could go for something along the lines of Every electron, on account of its angular momentum, is a small magnet (see Electron magnetic dipole moment). This angular momentum is composed of spin and orbital angular momentum components.

• TheBendster (talk) 8 July 2008, 08:19 (UTC)

I like the "angular momentum" idea. :-) --Steve (talk) 01:15, 9 July 2008 (UTC)

Change

change BC to BCE —Preceding unsigned comment added by 220.244.220.27 (talk) 01:23, 15 April 2009 (UTC)

Revisions needed

The various topics lack citations and are not all consistent with the exposition of the main articles. For example, spin glass. Brews ohare (talk) 23:02, 3 June 2009 (UTC)

Monopols

in resent since a singular magnetism has been found this was posted in the paper Science they found it while studding the " strange " material holmiumtitanat i do not have a reference outside this paper but i think it should be sufficient for the outdated stand i put the page on.MELISASIMPSONS (talk) 11:07, 29 December 2009 (UTC)

I'm familiar with that paper. They did not find "magnetic monopoles", they found something different that looks a little bit similar to them. See here for more details. I'm removing your {{UpdateWatch}} template, there's nothing outdated about this article's description of magnetic monopoles. --Steve (talk) 17:30, 29 December 2009 (UTC)

In Our Time

The BBC programme In Our Time presented by Melvyn Bragg has an episode which may be about this subject (if not moving this note to the appropriate talk page earns cookies). You can add it to "External links" by pasting * {{In Our Time|Magnetism|p003k9dd}}. Rich Farmbrough, 03:17, 16 September 2010 (UTC). hi you are silly! —Preceding unsigned comment added by 80.42.235.77 (talk) 16:17, 7 February 2011 (UTC)

Content analysis of magnetism

what is content analysis of magnetism? —Preceding unsigned comment added by 115.248.220.161 (talk) 04:46, 18 December 2010 (UTC)

Non-Magnetic substances

Copper is STRONGLY diamagnetic, meaning it repels a magnetic field; diamagnetism is correctly defined in the article. A term like 'non-magnetic' is very elementary school science in its simplicity. As the article also states, all materials are affected upon by magnetic fields in some way. Materials are ferromagnetic, strongly magnetic like iron and is alloys; paramagnetic, or not able to maintain their own magnetic domains/field but attracted to magnets, and diamagnetic, or repulsive/repulsed by magnetic fields. The degree of ferro-, dia-, and para- magnetism can vary between different elements and compounds. However, nothing is strongly "non-magnetic." Copper definitely needs to be purged from this list. A pure copper penny can be made to levitate and spin in very strong magnetic fields. That's "non-magnetic" ??? Nope. —Preceding unsigned comment added by 75.175.177.172 (talk) 03:49, 5 March 2011 (UTC)

Is the SVG version better or worse?

Is it just me, or is the SVG version of the magnetism hierarchy (File:Magnetism.svg) harder to read than the JPEG version (File:Magnetism.JPG)? RockMagnetist (talk) 00:35, 24 November 2011 (UTC)

I like the JPEG version better.--LaoChen (talk) 15:13, 24 November 2011 (UTC)