The force required to accelerate a radiating charge

Click For Summary

Discussion Overview

The discussion revolves around the force required to accelerate a radiating charge, particularly in a non-relativistic context. Participants explore the implications of radiation on the force needed for constant acceleration, considering concepts such as energy conservation and the effects of radiation reaction.

Discussion Character

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

Main Points Raised

  • One participant questions the force needed to accelerate a non-relativistic point charge while accounting for radiation, suggesting that the force must do extra work to overcome the Larmor power.
  • Another participant argues that the emitted radiation acts as a small drag force rather than the primary accelerating force, which typically comes from an external electric or magnetic field.
  • A participant seeks clarification on the force required for constant acceleration without 'jerk', noting the challenge of conserving energy when the velocity is zero.
  • Another participant points out that while there is no radiation reaction force for constant acceleration, there must still be some force inputting energy to the charge, raising questions about the source of this energy.
  • A participant shares a link to a resource discussing the dilemma of energy conservation in this context.

Areas of Agreement / Disagreement

Participants express differing views on the role of radiation in the context of accelerating charges, with no consensus reached on the nature of the forces involved or the implications for energy conservation.

Contextual Notes

Participants highlight limitations in understanding the relationship between radiation reaction and constant acceleration, as well as the challenges in defining the necessary force input under these conditions.

blgeo
Messages
4
Reaction score
0
If we try to treat a non-relativistic point charge, what force do we need to accelerate it uniformly, when we take the fact that it radiates into account? I assumed the force would do the necessary extra work so that:

F dx = d(1/2 mv^2) + P dt;

where P is the Larmor power, but at any point where the velocity is 0 this would imply an infinite force. What am I missing?
 
Physics news on Phys.org
You've got the cart in front of the horse.

The emitted radiation is a very, very small drag force on the electron, not the accelerating force, which usually comes from an applied electric or magnetic field.
 
I'm assuming a case with no 'jerk' (constant acceleration), and I would like to figure out what force we need to put in in order to achieve this - I'm aware the radiation is effectively a small drag on the electron, but what is the required additional input force to keep acceleration constant, and conserve energy? I don't think Abraham Lorentz is much help as this applies to non-constant a. How do we conserve energy when a dot = 0?
 
In case of no jerk,you can see there is zero radiation reaction force but you also know that an accelerating charge radiates,so there is supposed to be some force putting energy into it.But the problem is from where it will come because radiation reaction is zero for constant acceleration.You can see for this dilemma here
http://www.mathpages.com/home/kmath528/kmath528.htm
 
Just what I was looking for - thanks andrien
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 5 ·
Replies
5
Views
478
  • · Replies 6 ·
Replies
6
Views
994
  • · Replies 6 ·
Replies
6
Views
536
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 6 ·
Replies
6
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K