Electric field of a moving charge?

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Discussion Overview

The discussion centers around the calculation of the electric field generated by a moving charge at a specific point in space and time. Participants explore the applicability of Coulomb's Law in this context and the concept of retarded potentials, as well as the relationship between electric and magnetic fields in dynamic situations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether Coulomb's Law, which relates electric field strength to distance, can be applied to a moving charge or if it is only valid for static charges.
  • Another participant notes that calculating the electric and magnetic fields of a moving charge involves complex mathematics and suggests using retarded potentials for derivation.
  • A participant seeks clarification on what retarded potentials are and why Coulomb's Law cannot be used in this scenario.
  • It is mentioned that Coulomb's Law applies to static charges or in integral form for charge distributions, and that the presence of a magnetic field complicates the situation.
  • Discussion includes the nature of magnetic fields and their characterization as conservative or non-conservative, with a focus on the work done on a particle moving in a magnetic field.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of Coulomb's Law to moving charges, and there is no consensus on the characterization of magnetic fields or the use of retarded potentials. The discussion remains unresolved regarding the best approach to calculate the electric field in this context.

Contextual Notes

Limitations include the complexity of the mathematics involved in deriving fields from retarded potentials and the assumptions regarding static versus dynamic charges. The discussion does not resolve the mathematical steps necessary for these calculations.

physics user1
I have a moving charge in a generic motion, and I pick a point p, how do I get the electric field caused by the charge on point p, at any time?
Can I use the coulomb definition of electric field that relates it's strenght with the Distance?
Or does that law works only when the charge is static?
How can I Do?
Btw this is not a homework question oregarding something, I'm just wondering cause I never encountered such a problem and they told me that coulomb law work for electrostatics

I know all maxwell equations
 
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First, I have to tell you that in order to calculate the fields (electric and magnetic) of a moving charge , the math are somewhat involved. You can derive the fields from the (retarded) potentials. For a such derivation you can take a look here. Also, for a derivation using first principles take a look here.
 
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QuantumQuest said:
First, I have to tell you that in order to calculate the fields (electric and magnetic) of a moving charge , the math are somewhat involved. You can derive the fields from the (retarded) potentials. For a such derivation you can take a look here. Also, for a derivation using first principles take a look here.

What are the retarded Potential? Why can't I use the coulomb Law?
The magnetic field is not conservative, how can it have a Potential?
 
Cozma Alex said:
What are the retarded Potential?

Retarded potentials are the electromagnetic potentials generated by time-varying electric current or charge distributions in the past. For more see Wikipedia.

Cozma Alex said:
Why can't I use the coulomb Law?

Coulomb's Law can be applied for static charge(s) or in integral form for charge distributions. Now, if we have a moving charge we have a magnetic force as well. So, we can't consider only the electrostatic force in this case.

Cozma Alex said:
The magnetic field is not conservative, how can it have a Potential?

The magnetic field itself is neither conservative nor non-conservative. In order to characterize a field in general as conservative or not, you have to take the force applied on a particle moving along any closed path and calculate the net work done. But in this case, the magnetic field (effectively force) on a moving particle is at right angles to the motion so the work is always zero. So, there is no proper application of the concept.
 
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