Why does the movement of electrons create fields?

[spagettot]

TL;DR

i am learning electricity and overall physics and i just cant wrap my head around electricity (i am a beginner with not that much knowledge or experience)

i know the electron are not the one to transfer energy and that the electric and magnetic field are the ones doing the job but why is the field created in the first place and even the "energy flowing with the fields" is still pretty abstract to me

 

[anuttarasammyak]

Electrons are source of electric field. Gauss’s law describes it. When they are in motion magnetic field is also generated. Ampere’s law describes it. After we fully know them, we may investigate energy of fields.
https://www.feynmanlectures.caltech.edu/II_04.html I
Is a good reading to get the basics.

 

[spagettot]

so is it like all the electron fields make a bigger field ?

 

[spagettot]

no no no i think i understand now, all the fields in the electrons act a bit like a crowed of people individuals have interact with each other and the environment but they're combined interaction make the whole field right ?

 

[berkeman]

From your New Member Introduction thread:

i am currently learning chemistry, physics, math, electricity and all that stuff with a background of programming in C and asm,

Are you learning these subjects in high school, or self-studying them after high school, or learning them in some other way? It would be good to know your level of education so far so that we can tailor our replies to that level. For example, have you learned any calculus so far?

 

[spagettot]

From your New Member Introduction thread:


Are you learning these subjects in high school, or self-studying them after high school, or learning them in some other way? It would be good to know your level of education so far so that we can tailor our replies to that level. For example, have you learned any calculus so far?

im self studying, i am 16 and learning calculus but still a BIG NOOB with some basics here and there, im doing all this for fun

 

[berkeman]

Good for you! As you get more calculus under your belt, you can have a look at Maxwell's Equations. They are the equations that we use to do the calculations for how moving charges create Electromagnetic Radiation (light, radio waves, etc.).

https://en.wikipedia.org/wiki/Maxwell's_equations

Edit/Add: https://en.wikipedia.org/wiki/Electromagnetic_wave_equation

 

[Matterwave]

It's not that the movement "creates the fields". Fields are not created, they simply are. Just as electrons simply are.

An electron at rest "has an electric field". An electron in motion "has a magnetic field". Our description of electromagnetic theory requires the electric and magnetic fields to be there. The electric and magnetic fields provide a way for distant charged particles to exert forces on each other.

Creation implies some process. There is no process here.

 

[spagettot]

It's not that the movement "creates the fields". Fields are not created, they simply are. Just as electrons simply are.

An electron at rest "has an electric field". An electron in motion "has a magnetic field". Our description of electromagnetic theory requires the electric and magnetic fields to be there. The electric and magnetic fields provide a way for distant charged particles to exert forces on each other.

Creation implies some process. There is no process here.

i just understood that, the field is not generated but more of an interaction with space, just like a hand can just touch and interact with things without generation said action (if the example is clear) thank you

 

[Matterwave]

i just understood that, the field is not generated but more of an interaction with space, just like a hand can just touch and interact with things without generation said action (if the example is clear) thank you

I might not phrase things that way, but I also can't tell exactly how you are thinking of things. Maybe you would like to rephrase it?

 

[spagettot]

I might not phrase things that way, but I also can't tell exactly how you are thinking of things. Maybe you would like to rephrase it?

that fields are interactions not something generated there how an electron for example interacts with space (it took me a very long time to have this mental model and i dont know how to explain it or if its valid)

 

[berkeman]

I don't know if it will help your intuition, but check out the animation of a dipole antenna at this Wikipedia page:

https://en.wikipedia.org/wiki/Dipole_antenna

It shows how the currents flow in the antenna wires and how the charges flow to generate those currents. It also shows how those charge movements and currents launch the EM wave that flows away from the antenna (at the speed of light). The animation says it is for receiving an EM wave, but the process is pretty much the same for transmitting as receiving.

 

[PeroK]

that fields are interactions not something generated there how an electron for example interacts with space (it took me a very long time to have this mental model and i dont know how to explain it or if its valid)

I don't know what saying an electron interacts with space might mean.

Charged particles generate fields. Fields generate forces on other charged particles. Those particles moves through spacetime according to Newton's second law. That, in a nutshell, is how classical EM works. It's a theory in which those things are essentially the postulates. There is no deeper explanation. They are the starting point. Coulomb's law etc.

 

[Matterwave]

that fields are interactions not something generated there how an electron for example interacts with space (it took me a very long time to have this mental model and i dont know how to explain it or if its valid)

I agree with "not generated". It is good to go away from the idea that fields are created or generated, they just "are". In every day talk, we might be sloppy with our word usage.

My mental model of the E&M fields is that at each point in space they are represented by a small arrow.

The small arrow for the electric field tells you "if I placed a small charge here, in what direction will that charge accelerate?". The answer depends on the sign of the charge.

The small arrow for the magnetic field tells you "if I placed a small charge here moving at a certain velocity, in what direction will the charge accelerate?". The answer here depends on the sign of the charge and also the direction of the velocity of the charge.

The total force (which gives an acceleration) on that small charge is given by the Lorentz force law. Don't let the mathematical symbols worry you, but in math language, the force exerted on that small charge is:

$$\vec{F}=q(\vec{E}+\vec{v}\times\vec{B})$$

Here, $\vec{F}$ is the force exerted on a charge $q$ (which can be positive or negative) moving at velocity $\vec{v}$. The $\vec{E}$ and $\vec{B}$ are the electric and magnetic fields respectively.

You don't need to understand the details of this formula yet, but know that this is how an actual interaction (a force) happens. A distribution of charges (a group of charges in some configuration moving around in space) has a electric and magnetic field which describes how a small "test" charge will be accelerated if it is placed in the field.

 

[PeroK]

If the fields just "are", why are they one thing rather than another?

What would an experimental physicist make of that?

 

[Matterwave]

If the fields just "are", why are they one thing rather than another?

Could you clarify your question?

Are you asking about why moving charges give rise to magnetic fields while stationary ones do not?

What would an experimental physicist make of that?

The experimental physicist should do the math to match experiment to theory. I see nothing in my description that would preclude that.

 

[spagettot]

its a force like gravity, gravity doesnt need to generate (i think i have good mental model but i am not sure this is confusing im gonna do a pause on electricity for now focus on mechanics and chemistry)

 

[Matterwave]

its a force like gravity

More precisely, in electrostatics (where my charge distribution doesn't move) the electric field gives rise to a force via $\vec{F}=q\vec{E}$ analogous to Newtonian gravity.

It's definitely a good idea to focus first on Mechanics, as many of the ideas there (especially force and acceleration) are crucial to the study of electromagnetic theory.

 

[anuttarasammyak]

so is it like all the electron fields make a bigger field ?

no no no i think i understand now, all the fields in the electrons act a bit like a crowed of people individuals have interact with each other and the environment but they're combined interaction make the whole field right ?

Each electron makes EM vector field individually. They superpose to be an observed EM vector.

 

[spagettot]

Each electron makes EM vector field individually. They superpose to be an observed EM vector.

if thats the case then i think i understand it a bit more than i though. thank you

 

[Averagesupernova]

As I understand there really is no magnetic field. Or more precisely said, a magnetic field is a special case of an electric field.
-
Get on YouTube and have a look. Be careful though, YouTube contains plenty of garbage. There are several channels you can trust that I believe explain this. Vocademy is one of them. Veritasium might be another that explained it. Either way, I believe Veritasium is generally trustworthy.

 

[renormalize]

As I understand there really is no magnetic field. Or more precisely said, a magnetic field is a special case of an electric field.

Actually, both the electric and magnetic fields are on the same footing as part of the Maxwell's "unified" electromagnetism. Any asymmetry between them springs from the empirical fact that we observe localized sources of the electric field (i.e., electric charges) but no analogous sources for the magnetic field (i.e., no magnetic monopoles).

 

[A.T.]

Or more precisely said, a magnetic field is a special case of an electric field.

Electric field and magnetic field are both components of the same (electro-magnetic) field. Saying one is a special case of the other makes no sense. They are rather complimentary.

 

[Averagesupernova]

Electric field and magnetic field are both components of the same (electro-magnetic) field.

As I understand it, you can have an electric field without a magnetic field. But you cannot have a normal circuit current without both. Do what I said and find the videos. Non-conservative fields are a different situation such as a changing magnetic field inducing a current in a closed ring conductor.

 

[Averagesupernova]

This is the one I'm referring to. It has been a while since I watched it. There are other YouTubers that have made videos that agree.

 

[Matterwave]

As I understand it, you can have an electric field without a magnetic field. But you cannot have a normal circuit current without both.

See @renormalize post #22. The asymmetry comes because magnetic monopoles, as far as we know, do not exist.

This asymmetry is indeed part of the universe as we know it. But it does not mean we should say "the magnetic field is a special case of the electric field".

It might help to see an illustration. When we express the EM field in naturally covariant language, we arrive at the antisymmetric electromagnetic Field Tensor (sometimes called the Faraday Tensor):

$$
F_{\mu\nu} = \begin{pmatrix}
0 & E_x/c & E_y/c & E_z/c \\
-E_x/c & 0 & -B_z & B_y \\
-E_y/c & B_z & 0 & -B_x \\
-E_z/c & -B_y & B_x & 0
\end{pmatrix}
$$

This tensor's components will mix when we perform lorentz boosts.

 

[A.T.]

This is the one I'm referring to.

Where exactly does it state that "a magnetic field is a special case of an electric field"? Please provide the time and exact quote.

 

[Averagesupernova]

My intent here was to share a video. It right, it's wrong, it's whatever. I'm not claiming the existence of magnetic monopoles. Watch the video, or don't. That's it, I'm done.
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Edit:
My phrase "special case" might not be mentioned specifically in the video. Obviously I'm not going to link the video and claim it's saying something that it's not. The point is to watch it. It's not a contest for someone to be able to say "well that was never said specifically". I don't believe we are in court here.