# Trying to understand magnetism [closed]

Ok, we have electric field, and we understand it good.

Classic

It's a potential force field, that oscillates by fundamental particles, that haves electrical charge. Positive and negative charges attractes, pos and pos, as well as neg and neg moves out. As far, as I understand, electric field exists always - it doesn't depends on is particle moving or not.

And quantum

As quantum physics says, particle with electrical charge oscillate the electromagnetic field(emf), and oscillations of EMF is photons - an interraction carier. As I think(because there is no information i've could find), photons caries information about particle(like coordinates, or smth else), that generates it, then another paritcal absorb it, and then, in partical runs mechanism, that moves partical(attract or move out).

So what is magnetic field?

1)There is no particles that caries magnectic interraction.

2)If we look on two dissimilar particles, we can notice, that fields, generated by them are the same as magnetic field.

With arguments above I can assume, that electic field = magnetic field. In russian wikipedia wrote, that magnetic field generates by particles with magnetic moment, and particles with charge, that moves; and it influence on particles with magnetic moment, and particles with charge, independing on their movent. Click on magnetic moment and reading what it is: "An quantity that characterizing magnetic properties of substance...(another unhelpfull text)...As quantum physics says, it conditioned by it's own mechanic moment - spin". Click on spin - it describes how particle rotates but it doesn't rotates. Good. So, what is magnetic moment - I didn't understood.

My teacher said, that electiac field moves charges, but magnetic field only changes their direction. Is it true?

And what about theory of relativity? Magnetic field interract with charges that moves(but they all moves). If it will be moving with the same speed, that charges, there wouldn't be a magnetic field?

• If you want to udnerstand magnetism, you shouldn't try to "take it all altogether". Go step by step. First you should understand the electric field. Then the magnetostatic field, and then the electromagnetic induction. This all being "classic", meaning non quantum. You'll have time in life to learn about QFT., but it is important to set a good basis. – FGSUZ Jan 19 '18 at 18:48
• It would take several textbooks to answer your questions to your satisfaction, so I'm voting to close this question as too broad. That said, these are the right questions to ask! I highly encourage you to spend some time reading the classic texts (Griffiths is a good start for electrodynamics) to try and get some intuition on these matters. – probably_someone Jan 19 '18 at 18:56
• @FGSUZ, but I understanding electric field. I don't understand what exactly magnetic field is – Артур Клочко Jan 19 '18 at 18:59
• That's nice. Then you should start with the magnetostatic field part of electromagnetism books. – FGSUZ Jan 19 '18 at 19:02
• @FGSUZ, ￢_￢ ... – Артур Клочко Jan 19 '18 at 19:07

Spin is an abstract notion in quantum mechanics, it's nothing like the spin of a soccer ball. The word spin was originally used as an analogy with an ordinary spinning object, to explain how the electron could be thought of as having energy, apart from its orbital energy.

100 years ago, physicists found an energy associated with the electron that they could not explain in their early quantum theory, so they used the image that the electron has an extra energy derived from spinning, but this is just a (incorrect) mental picture.

But if you accept that spin is an analogy, and not real, then you might accept that the electron has an axis to spin around.

This imaginary axis of rotation can be directly linked to the real magnetic field created by an electron,

If the electron is visualized as a classical charged particle literally rotating about an axis with angular momentum L, its magnetic dipole moment μ is given by

$${\boldsymbol {\mu }}={\frac {-e}{2m_{\text{e}}}}\mathbf {L} ,$$ where $m_e$ is the electron rest mass

When you say:

And what about theory of relativity? Magnetic field interract with charges that moves(but they all moves). If it will be moving with the same speed, that charges, there wouldn't be a magnetic field?

This question, as the comment above suggests, is something that you could leave until later.

• You wrote dipole moment above the equation. Dipole means 2, but electron is single. How should I understand it? – Артур Клочко Jan 19 '18 at 19:16
• Say we bring an large external magnetic field close to the "spinning" electron. The moment is an indication of how the electron will align with the strength and direction of the stronger second magnetic source. – user181180 Jan 19 '18 at 19:22
• Okay, but dipole, what means dipole in this case? – Артур Клочко Jan 19 '18 at 19:26
• You are a real physicist:) There are now two charges, (dipole two poles) as above, so you could say that the dipole is the electron and the source of the external field producing a torque to align their axis, but this is a crude way of putting it. If you read en.m.wikipedia.org/wiki/Magnetic_moment it will go into more detail. – user181180 Jan 19 '18 at 19:56
• Oh, now I understood. In this case minus of dipole is electron, and plus is external field... External field, you mean it is an electric field somewhere from outsource? Please, don't say that external field is magnetic field, because we are talking, that the source of magnetic field is dipole and than, we get a loop... – Артур Клочко Jan 19 '18 at 20:06