Electric and Magnetic Fields, Photons, Charges

In summary, magnetic fields create electric fields in a perpendicular direction. They are not equivalent. Electric fields are propagated through lines of force, not in one direction.
  • #1
Surya97
42
3
I know that magnetic fields create moving charges (an electric current) normal to the plane of the magnetic force lines. I also have heard that magnetic and electric fields create each other in a perpendicular direction to the other (badly worded). Electric currents are moving charges (usually electrons), but electric fields are propagated through lines of force, not in one direction. How are these equivalent? Also, if there are no charges in the area of the magnetic field (it is emitted from a ferromagnetic substance), then how does the magnetic field create moving charges?

I know that oscillating magnetic and electric fields is basically what EM radiation is. However, I cannot visualize light (a transverse wave with a finite amplitude, frequency and wavelength which travels in a single direction) as two fields that turn into each other rapidly. If that were true, then EM waves would be projected in all directions in a sphere from the source. If a photon is equivalent to a standing wave probability function, and photons move in a single direction, how does this make sense (as these two things are equivalent, but seem different)?
 
Physics news on Phys.org
  • #2
Surya97 said:
I know that magnetic fields create moving charges (an electric current) normal to the plane of the magnetic force lines.

A changing magnetic field creates an electric field, not an electric current.

Surya97 said:
Electric currents are moving charges (usually electrons), but electric fields are propagated through lines of force, not in one direction. How are these equivalent?

They are not. An electric charge is a piece of matter with the property that it generates/affects the EM field around it. An electric field is the electric portion of the EM field.

Surya97 said:
I know that oscillating magnetic and electric fields is basically what EM radiation is. However, I cannot visualize light (a transverse wave with a finite amplitude, frequency and wavelength which travels in a single direction) as two fields that turn into each other rapidly. If that were true, then EM waves would be projected in all directions in a sphere from the source.

This isn't true, but unfortunately I lack the knowledge to really explain why. In any case, neither the electric nor magnetic portion of the EM radiation (EM wave) turns into the other. If that were true then the two portions would be 90 degrees out of phase with one another, such that when one is at maximum amplitude the other is at minimum. This is not the case. Both portions are in phase with one another and reach maximum and minimum amplitude at the same time.

Surya97 said:
If a photon is equivalent to a standing wave probability function, and photons move in a single direction, how does this make sense (as these two things are equivalent, but seem different)?

Honestly I wouldn't even begin to try to understand the details of how photons work until you get a better understanding of classical EM theory first. The idea that you can even say which path a photon took is problematic in quantum theory (problematic in that you can't!).
 
  • Like
Likes Surya97
  • #3
Surya97 said:
but electric fields are propagated through lines of force, not in one direction.
This statement is nonsense. Electric and magnetic fields satisfy Maxwell's equations.

Surya97 said:
Also, if there are no charges in the area of the magnetic field (it is emitted from a ferromagnetic substance), then how does the magnetic field create moving charges?
It does not. Currents are necessary to create a magnetic field, but it is notgoing to be only where the currents are. Again, this is described by Maxwell's equations.
Surya97 said:
If that were true, then EM waves would be projected in all directions in a sphere from the source.
What makes you think this cannot be the case? Do you think the Sun only shines towards Earth?

However, it is not necessarily the case depending on how the light is created and focused.

Surya97 said:
If a photon is equivalent to a standing wave probability function, and photons move in a single direction, how does this make sense (as these two things are equivalent, but seem different)?
You really should not think in terms of photons here. They are among the absolutely most difficult particles to quantise. To put it short: no, photons are not waves of probability. No, photons do not move in a single direction. No, it does not make sense because you are using a mixture of popularised physics and trying to put pieces of it together. You will not learn physics in this way. You will learn physics by studying physics for real.
 
  • Like
Likes Surya97 and vanhees71
  • #4
Surya97 said:
I know that magnetic fields create moving charges (an electric current) normal to the plane of the magnetic force lines. I also have heard that magnetic and electric fields create each other in a perpendicular direction to the other (badly worded). Electric currents are moving charges (usually electrons), but electric fields are propagated through lines of force, not in one direction. How are these equivalent? Also, if there are no charges in the area of the magnetic field (it is emitted from a ferromagnetic substance), then how does the magnetic field create moving charges?

I know that oscillating magnetic and electric fields is basically what EM radiation is. However, I cannot visualize light (a transverse wave with a finite amplitude, frequency and wavelength which travels in a single direction) as two fields that turn into each other rapidly. If that were true, then EM waves would be projected in all directions in a sphere from the source. If a photon is equivalent to a standing wave probability function, and photons move in a single direction, how does this make sense (as these two things are equivalent, but seem different)?
First of all there are not two fields but only one, the electromagnetic field. The split in electric and magnetic components is dependent on the frame of reference and chosen just for convenience of the calculation.

Then, do not even try to think about photons before you haven't understood the classical theory. Photons cannot be visualized as massless little billard balls but only described using relativistic quantum field theory, which tells you that there is not even a position operator in the literal sense for a single-photon state.
 

1. What are electric and magnetic fields?

Electric and magnetic fields are invisible forces that surround charged particles and magnets. They exert a force on other charged particles and can cause them to move or interact with each other.

2. What are photons?

Photons are tiny particles of light and electromagnetic energy. They have no mass and travel at the speed of light. They are the basic unit of light and are responsible for all electromagnetic interactions.

3. How do electric charges interact with each other?

Electric charges interact through the exchange of photons. Like charges repel each other, while opposite charges attract. The strength of the interaction is determined by the size of the charges and the distance between them.

4. Can electric and magnetic fields be shielded?

Yes, electric and magnetic fields can be shielded by certain materials such as metal. These materials contain free electrons that can absorb and redirect the electric and magnetic fields, reducing their strength.

5. What are the units of electric and magnetic fields?

Electric fields are measured in volts per meter (V/m) and magnetic fields are measured in teslas (T). The strength of these fields is also influenced by the distance from their source, with the strength decreasing as the distance increases.

Similar threads

  • Quantum Physics
Replies
29
Views
2K
Replies
27
Views
2K
Replies
23
Views
1K
Replies
6
Views
749
  • Quantum Physics
Replies
0
Views
121
Replies
33
Views
2K
  • Quantum Physics
Replies
4
Views
1K
Replies
12
Views
959
  • Quantum Physics
Replies
12
Views
1K
  • Special and General Relativity
Replies
4
Views
131
Back
Top