Electric Charge and Magnetism: Constant or Varying Magnetic Field?

Click For Summary

Discussion Overview

The discussion revolves around the nature of magnetic fields generated by moving electric charges, specifically addressing whether a constant velocity results in a constant magnetic field or a time-varying one, and how acceleration affects this. The conversation also touches on the implications of constant current in wires and the relationship between electric and magnetic fields in various scenarios.

Discussion Character

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

Main Points Raised

  • Some participants propose that a charge moving with constant velocity generates a constant magnetic field, while others suggest it may vary with time if the charge is accelerated.
  • There is a discussion about whether a wire with a constant current creates a magnetic field, with some affirming that it does create a constant magnetic field.
  • One participant references the Biot-Savart law to support the claim that a constant current generates a constant magnetic field, while also noting that acceleration leads to radiation and a time-varying magnetic field.
  • Another participant introduces the Lienard-Wiechert potentials, stating that while there is no explicit time dependence, the input variables are functions of time, leading to a time-varying result.
  • There is a correction regarding the interpretation of time dependence in the context of the Lienard-Wiechert potentials, with some participants acknowledging confusion over the implications of the variables involved.
  • Some participants clarify that fields generated by the Biot-Savart law or Lienard-Wiechert potential for constant velocity do not produce radiation, although the fields change as the charge moves.

Areas of Agreement / Disagreement

Participants express differing views on whether a constant magnetic field is produced by a charge moving at constant velocity, with some asserting it is constant while others argue it may vary under certain conditions. The discussion remains unresolved with multiple competing views present.

Contextual Notes

Participants highlight the complexity of the relationship between electric and magnetic fields, particularly in relation to time dependence and the conditions under which radiation is produced. There are references to specific laws and equations that may require further clarification or context.

Who May Find This Useful

This discussion may be of interest to those studying electromagnetism, particularly in understanding the behavior of magnetic fields in relation to moving charges and the implications of constant versus varying conditions.

Dikshant
Messages
12
Reaction score
0
If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?
 
Physics news on Phys.org
Dikshant said:
If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?
Does a wire with a constant current through it create a magnetic field?
 
Vagn said:
Does a wire with a constant current through it create a magnetic field?
Thanks for reply,but m already a bit confused and that's a different case.
 
Vagn said:
Does a wire with a constant current through it create a magnetic field?
Yeah,a constant magnetic field
 
ChrisVer said:
yes it generates a constant in time magnetic field following the Biot Servart law
http://maxwell.ucdavis.edu/~electro/magnetic_field/pointcharge.html

If it is accelerated it is going to generate radiation (time varying magnetic field)
And
ChrisVer said:
yes it generates a constant in time magnetic field following the Biot Servart law
http://maxwell.ucdavis.edu/~electro/magnetic_field/pointcharge.html

If it is accelerated it is going to generate radiation (time varying magnetic field)

And what happens when a varying electric field is working in an area??
ChrisVer said:
yes it generates a constant in time magnetic field following the Biot Servart law
http://maxwell.ucdavis.edu/~electro/magnetic_field/pointcharge.html

If it is accelerated it is going to generate radiation (time varying magnetic field)[/QAnd
 
Dikshant said:
If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?
The fields from a moving charge are given by the Lienard Wiechert potentials

http://en.wikipedia.org/wiki/Liénar...onding_values_of_electric_and_magnetic_fields

It doesn't have an explicit time dependence, but the input variables are functions of time so the result is also.
 
Yes you are right DaleSpam...
Indeed, I misinterpreted this...I also thought about that when I saw the [itex]r[/itex] in the equation, but then... I got confused with the [itex]u=const[/itex] case not generating electromagnetic radiation... but the EM radiation is something different (has to do with the Poynting vector as well)...
 
  • #10
Yes that is correct. The fields generated by the Biot Savart law or the Lienard Wiechert potential for constant velocity do not generate "radiation". The fields stay localized to the charge. They change over time, as the charge moves, but their relationship to the charge doesn't change.
 
  • #11
Thank you all
 

Similar threads

Undergrad Does a time varying magnetic field in vacuum produce electric field or not?
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad Can nested solenoids trap particles?
  • · Replies 12 ·
Replies
12
Views
1K
Undergrad Charge movement relative to magnetic field frame dependence/invariance
  • · Replies 5 ·
Replies
5
Views
2K
High School Why doesn't a charged particle moving at a constant speed radiate?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Why charge density of moving dipole is dependent on time?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Small question about constantly accelerating charges
  • · Replies 10 ·
Replies
10
Views
1K
High School Thought Experiment on Charge Carriers and Electrical Conduction
  • · Replies 3 ·
Replies
3
Views
1K
Undergrad Question on Hall Effect and magnetic force
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Slowing down a moving electric charge
  • · Replies 5 ·
Replies
5
Views
1K
Undergrad Explaining the magnetic (cable) paradox
  • · Replies 5 ·
Replies
5
Views
2K