Poynting vector - uniform vs accelerated charge

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SUMMARY

The discussion centers on the distinction between radiation emitted by accelerating charges versus uniformly moving charges, specifically in the context of the Poynting vector. An accelerating charge emits electromagnetic radiation because the Poynting vector points out of the volume, indicating energy flow, while a uniformly moving charge does not emit radiation as its Poynting vector points into the volume, signifying no energy loss. Additionally, it is established that there is no inertial frame of reference for an accelerating charge where it remains stationary, unlike a uniformly moving charge. The detection of radiation from an accelerating charge is contingent upon the observer not being in an accelerating frame.

PREREQUISITES
  • Understanding of the Poynting vector in electromagnetic theory
  • Familiarity with the concepts of charge motion and radiation
  • Knowledge of inertial and non-inertial reference frames
  • Basic principles of electromagnetism and wave propagation
NEXT STEPS
  • Study the mathematical formulation of the Poynting vector in electromagnetic fields
  • Explore the implications of charge acceleration on electromagnetic radiation
  • Investigate the role of reference frames in detecting radiation from charges
  • Review advanced topics in classical electrodynamics, particularly Larmor's formula
USEFUL FOR

Students of physics, particularly those focusing on electromagnetism, researchers in theoretical physics, and educators seeking to clarify concepts related to charge motion and radiation.

arlesterc
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I am trying to understand why an accelerating charge emits radiation/electromagnetic waves but a uniformly moving one does not. I saw one video on Youtube where it seemed that it was explained by the fact that with a uniformly moving charge the Poynting vector was pointing 'in to the volume' - no energy was flowing out - but that with an accelerating charge the Poynting vector was pointing 'out of the volume' hence there was energy out that would be detected as electromagnetic waves. Is that the gist of it?
 
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For a uniformly moving charge there is an inertial frame of reference in which the charge is not moving and does not radiate. For an accelerated charge there is no inertial frame of reference in which the charge is stationary.. However there is more to the story; for an accelerated charge, radiation is only detected if the detector is not accelerating with the charge. You might want to look at the thread at https://www.physicsforums.com/threa...ravitational-field.950608/page-2#post-6020694

The mentors and forum staff were most patient with my questions in that thread.
 

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