Do Frame Dependent Charges Radiate?

  • Context: Graduate 
  • Thread starter Thread starter jartsa
  • Start date Start date
  • Tags Tags
    Charges Frame
Click For Summary

Discussion Overview

The discussion revolves around the behavior of an electric current in a moving loop of wire, particularly focusing on whether shaking the loop results in the emission of electromagnetic (EM) waves. The conversation touches on concepts of inertial and non-inertial reference frames, and how these affect the radiation of EM waves from the loop.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests that shaking one side of a moving loop of wire, which is considered an electric dipole, would result in the observation of EM waves.
  • Another participant argues that while the loop is being shaken, it is not in any inertial reference frame, implying that this affects the radiation of EM waves.
  • A different participant questions the reasoning behind the assertion that the loop exits all inertial reference frames when shaken, seeking clarification on the definitions of inertial and non-inertial frames.
  • One participant emphasizes that shaking the loop requires a force, thus indicating it is not in an inertial reference frame during that action.
  • Another participant suggests that the phrase "not in any inertial reference frame" may be misleading and proposes a distinction between being at rest relative to an inertial frame and being in a non-inertial frame.
  • One participant argues that the circuit should be considered from the perspective of an inertial observer, maintaining that shaking the loop will indeed lead to the radiation of EM waves due to the acceleration of charge distributions.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of inertial versus non-inertial reference frames, particularly in relation to the shaking of the loop and its ability to radiate EM waves. The discussion remains unresolved with multiple competing interpretations of the scenario.

Contextual Notes

There are unresolved assumptions regarding the definitions of inertial and non-inertial frames, as well as the conditions under which the loop radiates EM waves. The discussion reflects a range of interpretations that depend on these definitions.

jartsa
Messages
1,582
Reaction score
141
Let's say there's an electric current in a neutral loop of wire. Then we change to a frame where the loop is moving. That makes the loop an electric dipole, for us.

Then somebody shakes one side of the loop, the positive side for example.

Do we observe EM-waves?

Here's a picture of the loop moving to the right:
Code:
  +
  O
  -
---->
 
Last edited:
Physics news on Phys.org
While the loop is being shaken it is not in any inertial reference frame.

And yes, it will radiate EM waves, but it is much more effective to modify the current than to shake the loop.
 
UltrafastPED said:
While the loop is being shaken it is not in any inertial reference frame.
Why not? He specifically said, "we change to a frame where the loop is moving". Would you say the loop is in the inertial reference frame in which it is moving but then when someone shakes one side of the loop it some how exits that and all other inertial reference frames? This doesn't make any sense to me. Please elaborate.
 
jartsa said:
Then somebody shakes one side of the loop, the positive side for example.

... and then somebody shakes it. Shaking requires a force; if it feels a force it is not in an inertial reference frame.
 
UltrafastPED said:
While the loop is being shaken it is not in any inertial reference frame.
I think ghwellsjr is objecting to the phrase "not in any inertial reference frame" when you really mean "not at rest relative to any inertial reference frame".
 
  • Like
Likes   Reactions: 1 person
UltrafastPED said:
... and then somebody shakes it. Shaking requires a force; if it feels a force it is not in an inertial reference frame.
Before somebody shakes it, is it in the inertial reference frame in which the OP said it is moving?
 
I think it's a bit misleading to say "something is in a inertial or non-inertial reference frame". The question is whether you describe a situation within an inertial or a non-inertial reference frame or to put it more physically whether the observer is in an inertial frame ("inertial observer") or accelerated relative to the class of inertial frames ("accelerated observer").

As described by the OP the circuit is always considered to be observed from an "inertial observer". I'd keep it in the reference frame, where it is initially at rest and then shaken. Of course, when it is shaken it will radiate em. waves. This is so because you have effectively accelerated charge distributions even if the wire is overall neutral due to relativistic effects of currents and charges.
 

Similar threads

Replies
7
Views
2K
  • · Replies 87 ·
3
Replies
87
Views
6K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 49 ·
2
Replies
49
Views
5K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 27 ·
Replies
27
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K