What's a magnetic field made of?

[Daecon]

I've been trying to remember when I realised I don't actually know.

 

A stream of electrons would be bent if it were to pass through a magnetic field, wouldn't it? So I don't think a magnetic field is actually made of electrons.

 

I can only assume it's some force-carrier particle that I've forgotten exists. What is it and how are they generated?

[moth]

i think photons mediate the magnetic field force.

apparently in something like a permanent magnet the orbits of electrons provide the moving charge needed to generate a magnetic field.

[epsilonbeta]

I think above knowing how it is created and knowing its affects, it is not known what its made out of, i don't think, don't take that as fact... its kinda like gravity, but there is more theoretical stuff on what gravity is made out of... but we don't know how to make gravity so...

 

of referenced from Wikipedia: http://en.wikipedia.org/wiki/Electromagnetism

 

Electromagnetism is the physics of the electromagnetic field, a field which exerts a force on particles with the property of electric charge and which is reciprocally affected by the presence and motion of such particles.

 

A changing magnetic field produces an electric field (this is the phenomenon of electromagnetic induction, the basis of operation for electrical generators, induction motors, and transformers). Similarly, a changing electric field generates a magnetic field. Because of this interdependence of the electric and magnetic fields, it makes sense to consider them as a single coherent entity - the electromagnetic field.

 

The magnetic field is produced by the motion of electric charges, i.e., electric current. The magnetic field causes the magnetic force associated with magnets.

Edited March 17, 2009 by epsilonbeta
gramer error

[cameron marical]

im still not really getting what makes something be attracted or repelled by an ion. i get the whole extra or missing electrons make it an electromagnetic feild, but what actually goes up to something and pulled it or pushes it. it cant just be that positive and negative want to come to eact other so they do. can it?

[lenvanzanten]

The following link may be helpfull in disclosing magnetic force.

Leonard

http://www.leonardswebpage.info/leonards/fw43.htm

[Sayonara]

It gives a 404 Not Found, I'm afraid.

[Klaynos]

Charged particles interact by sending virtual photons to each other.

 

I'd strongly suggest reading QED by Feynman. It's written for anyone to understand.

[morganparkar]

Hi Friend,

 

The magnetic field forms one aspect of electromagnetism. (See also relativistic electromagnetism.) In a simplified form the magnetic field can be thought of as the relativistic part of an electric field.

[Daecon]

So a magnetic field is made of virtual photons flowing between north and south poles?

 

How do they have enough force to cause physical (non-virtual) particles to change direction and things like that? Such as what happens with the Aurora Borealis or a compass needle?

[swansont]

They aren't flowing between the N and S poles, as such. The virtual photons are the force carriers. The field lines would be more representative of contour lines on a map telling you how hilly it is; where the field lines are closely packed the force is stronger.

 

What the field is "made of" may be borrowing too heavily on a mental construct that isn't accurate. Fields field lines are based on our models and descriptions of how things behave in the presence of charged particles, be they stationary or moving around.

 

The electric field, for example, is E = F/q, i.e. the force per unit charge a particle will feel. But with no charge there, there is no force. So is the field a real thing, or a description? If it's not a real thing, then it's not "made of" anything.

[Daecon]

Are virtual photon force carriers proven to be real, or are they just a theoretical explanation?

 

Your post reminded me of the two schools of through regarding gravity, either with it's own force carriers or from a bending of spacetime.

 

If virtual photons are a theoretical explanation, could a different sort of space bending explain a magnetic field, whereas instead of "mass" being manipulated by it (like gravity), "charge" is instead?

 

I'm not sure if I explained that clearly, do you understand what I'm thinking?

[Ecap]

I don't think a magnetic field is really made of anything. A magnetic field surrounds a magnet. The magnetic fields were "mapped" by observing the behavior of charges placed into the field.

[moth]

 

Your post reminded me of the two schools of through regarding gravity, either with it's own force carriers or from a bending of spacetime.

 

 

bent spacetime makes more sense to me, which is why it probably doesn't work that way.

would it be possible to tune a quantum dot to catch a virtual photon?

[north]

I've been trying to remember when I realised I don't actually know.

 

A stream of electrons would be bent if it were to pass through a magnetic field, wouldn't it? So I don't think a magnetic field is actually made of electrons.

 

I can only assume it's some force-carrier particle that I've forgotten exists. What is it and how are they generated?

 

I think your right though

 

electrons comprise the magnetic field

 

there are " clicks " so to speak when a magnetic field is induced upon an object

[Kaeroll]

This is something that's been bugging me for a while, though from a chemist's perspective.

 

swansont- your post, while insightful, perhaps doesn't answer the question.The field may be a theoretical construct or the like, but knowing that doesn't bring us much closer to the answer of how charge is transmitted. It might not be 'made of' anything.. but why should, for example, two electrons repel? The answer being 'they have like charges'. But what is charge? How is it felt through space? etc...

 

(Those are mostly rhetorical questions... I obviously don't expect you to produce a treatise on QED.)

[Klaynos]

Are virtual photon force carriers proven to be real, or are they just a theoretical explanation?

 

They are "proven".

 

Your post reminded me of the two schools of through regarding gravity, either with it's own force carriers or from a bending of spacetime.

 

The two are not mutually exclusive, gravity can be both a bend in spacetime and mediated by gravitons.

[swansont]

This is something that's been bugging me for a while, though from a chemist's perspective.

 

swansont- your post, while insightful, perhaps doesn't answer the question.The field may be a theoretical construct or the like, but knowing that doesn't bring us much closer to the answer of how charge is transmitted. It might not be 'made of' anything.. but why should, for example, two electrons repel? The answer being 'they have like charges'. But what is charge? How is it felt through space? etc...

 

(Those are mostly rhetorical questions... I obviously don't expect you to produce a treatise on QED.)

 

For the answer I second Klaynos's excellent suggestion of Feynman's QED. Photons are the force-carriers, and the understanding of those interactions is the basis of the electromagnetic force. ("charge is transmitted" is an awkward expression from a physicist's point-of-view). Fields and field lines are a conceptual tool that help us understand some of the effects.

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Merged post follows:

Consecutive posts merged

I think your right though

 

electrons comprise the magnetic field

 

there are " clicks " so to speak when a magnetic field is induced upon an object

 

Electrons most definitely do NOT comprise the electric field. comprise = "to be made up of" and you have electric fields where there are no charges. QED. (The other QED)

[Kaeroll]

Well, if both of you have recommended it I've no reason not to get a copy. Hopefully the university library has it. Cheers to both of you.

 

As I said, I naturally approach this from a chemist's perspective, and at my level of study it's very much a black-box. Polarity and charge drive ridiculous amounts of chemistry, but how they're carried ('transmitted' seemed the apt term to me, ah well) remains behind the veil as it were.

 

Again- cheers.

[Klaynos]

This is something that's been bugging me for a while, though from a chemist's perspective.

 

swansont- your post, while insightful, perhaps doesn't answer the question.The field may be a theoretical construct or the like, but knowing that doesn't bring us much closer to the answer of how charge is transmitted. It might not be 'made of' anything.. but why should, for example, two electrons repel? The answer being 'they have like charges'. But what is charge? How is it felt through space? etc...

 

(Those are mostly rhetorical questions... I obviously don't expect you to produce a treatise on QED.)

 

Charge is not transmitted. We don't know why things have charge, it's a fundamental thing it seems. Charged particles send photons to each other, these are vitrual photons, it's a bit complicated to explain, I would again strongly recommend reading QED it is a truly exceptional book, and short enough to read in a couple of days.

 

||edit And now I see the above posts...

[north]

Originally Posted by north

I think your right though

 

electrons comprise the magnetic field

 

there are " clicks " so to speak when a magnetic field is induced upon an object

 

Electrons most definitely do NOT comprise the electric field.

 

really

 

I thought we were talking about magnetic fields , rather than " electric fields "

 

 

comprise = "to be made up of" and you have electric fields where there are no charges. QED. (The other QED)

 

explain further

[Klaynos]

Magnetic and electric fields can be thought of as the same, they are completely unified by maxwell's equations.

 

Electrons have charge, they are not in themselves part of the field.

 

So you have an electron, with an electric field, you move it, it now has a magnetic and electric field. This field is outside of the electron, the electron itself is not the field...

 

In my above paragraph you can replace the word electron with any other charged particle.

[cameron marical]

so, this may be really wrong, but, do electrons make up a magnetic feild, or photons? whatever it is, does it ionize particles, and thats why things are attracted?

[morganparkar]

Hi,

 

 

Here i tell you ur answer.

 

The electromagnetic interaction is mediated by the constant exchange of photons from one charged object to another. The magnetic field is really just a classical approximation to the photon-exchange picture. In a moving reference frame, a magnetic field appears instead as a combination of a magnetic field and an electric field, so electric and magnetic fields are made of the same "stuff" (photons).

 

 

Thanks,

 

Parkar

[swansont]

really

 

I thought we were talking about magnetic fields , rather than " electric fields "

 

 

Same thing goes for magnetic fields. They are caused by moving charges (which can simply be from a change in frame of reference), but they are not made up of them, as Klaynos has also explained.

 

Electrons move within a wire. The magnetic field they create exists outside of the wire, where there are no electrons. Thus, the field cannot be made up of electrons.