Magnetic Field: Electric vs Pure?

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Discussion Overview

The discussion revolves around the relationship between electric and magnetic fields produced by charged particles, particularly at varying velocities, including relativistic speeds. Participants explore concepts related to electric field intensity, magnetic field generation, and the implications of Lorentz contraction, while also touching on atomic structure and the presence of unpaired electrons.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that when charged particles are stationary, they produce an electric field, which diminishes as they accelerate, while a magnetic field increases in intensity.
  • Others argue that the velocity of a particle does not affect the electric field at non-relativistic speeds, and that at relativistic speeds, Lorentz contraction leads to a higher-intensity electric field perpendicular to the particle's velocity.
  • One participant questions whether particles moving at the speed of light would produce a pure magnetic field without an electric field, suggesting that this is not the case.
  • There is a discussion about the nature of unpaired electrons in atoms, with some participants noting that an atom with unpaired electrons also has an electric field.
  • Another participant suggests that one can derive relationships between electric and magnetic fields using Lorentz transformations and Maxwell's equations, referencing a standard exercise involving an infinite line of charge.

Areas of Agreement / Disagreement

Participants express differing views on the effects of particle velocity on electric and magnetic fields, particularly regarding relativistic effects and the nature of fields produced by charged particles. No consensus is reached on whether particles can produce a pure magnetic field at the speed of light.

Contextual Notes

Limitations include assumptions about the definitions of electric and magnetic fields, the conditions under which Lorentz contraction applies, and the implications of atomic structure on field generation. Some mathematical steps and relationships remain unresolved.

Chemist@
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When charged particles aren't moving they produce an electric field. As the start to move and accelerate, the electric field intensity gets lower, but a magnetic field is being made and it increases in intensity. If the particles reach the speed of light will they produce pure magnetic field without the electric field?

An atom with unpaired electrons doesn't have a pure magnetic field, there is an electric one,too, right?
 
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The velocity of a particle effectively has no effect on the electric field at non-relativistic speeds. A moving particle will not have a lower intensity electric field. If the particle is moving at relativistic speeds, then the effects of Lorentz contraction will actually cause a higher-intensity field perpendicular to the velocity of the particle. When a particle is traveling near the speed of light, it will have the same electric field as if it were stationary, only it will be deformed by Lorentz contraction.
 
Chemist@ said:
When charged particles aren't moving they produce an electric field. As the start to move and accelerate, the electric field intensity gets lower, but a magnetic field is being made and it increases in intensity. If the particles reach the speed of light will they produce pure magnetic field without the electric field?
No.
An atom with unpaired electrons doesn't have a pure magnetic field, there is an electric one,too, right?
A "paired" electron is usually considered to be one that is paired with another electron with the opposite spin. But "unpaired electron" could be taken to mean that the number of electrons is not the same as the number of protons. So I am going to be careful:

An atom with the same number of electrons as protons also has an electric field.
 
Nessdude14 said:
The velocity of a particle effectively has no effect on the electric field at non-relativistic speeds. A moving particle will not have a lower intensity electric field. If the particle is moving at relativistic speeds, then the effects of Lorentz contraction will actually cause a higher-intensity field perpendicular to the velocity of the particle. When a particle is traveling near the speed of light, it will have the same electric field as if it were stationary, only it will be deformed by Lorentz contraction.

What happens with the magnetic field?

For now, thanks to both of you for the answers.
 
You can work it out yourself from the Lorenzt transformation and Maxwels equations ... the standard exercize given relativity students is to consider an infinite line of charge ... you should be able to work out the leectric field due to that. It is not moving so it has no magnetic field.

Now do the same for an observer moving parallel to the line.
Now, for that observer, the line of charges is moving - it's a current.

At relativistic speeds you'd get an appreciable length contraction - what does that do to the charge density? To the electric field? To the current? To the B field?

Look up "Faraday tensor".
 

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