EM Wave creation in different frames of reference

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SUMMARY

The discussion centers on the creation of electromagnetic (EM) waves from the perspective of two observers, S and A, in relation to a charged particle. Observer S, stationary relative to the particle, perceives no magnetic field, while Observer A, who accelerates back and forth, perceives the particle as accelerating and thus expects EM waves to be generated. The key conclusion is that the differing frames of reference lead to different interpretations of the particle's motion and the resulting electromagnetic phenomena, necessitating the application of special relativity to reconcile these observations.

PREREQUISITES
  • Understanding of electromagnetic theory, specifically the behavior of charged particles.
  • Familiarity with the concepts of frames of reference in physics.
  • Knowledge of special relativity and its implications on motion and electromagnetic radiation.
  • Basic grasp of classical physics principles related to acceleration and forces.
NEXT STEPS
  • Study the principles of special relativity and how they apply to electromagnetic radiation.
  • Explore the mathematical formulation of electromagnetic waves generated by accelerated charges.
  • Learn about the Lorentz transformations and their role in different frames of reference.
  • Investigate the implications of observer-dependent phenomena in classical and modern physics.
USEFUL FOR

Physicists, students of electromagnetism, and anyone interested in the implications of special relativity on electromagnetic wave generation and observer-dependent phenomena.

ealbers
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OK, I'm sure I'm just not thinking about this the right way, so please point out my simple mistake.

Imagine a charged particle and 2 observers.

Observer S is stationary relative to the charged particle, so sees no magnetic field from it.

Observer A moves back and forth in front of the particle, accelerating, then decelerating over and over, back and forth.

Would not Observer A see the charged particle as accelerating and decelerating, from their point of view/frame of reference?
Would not the acceleration of a charged particle from Observers A perspective create a EM wave which would propagate outwards?

Now from Observer S's perspective, there is just a charged particle and the other Observer moving around, no EM wave is created.

What am I missing??
Thanks for your time!
E
 
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Because S and the particle are moving back and forth (as opposed to inertially, in a straight line with constant speed) they know that they are being accelerated at each turnaround. S and A are not equivalent observers; if they're both holding a mass on a spring, S's spring is alternately tensing and relaxing while A's is not. Thus, they both know to do the calculations for an accelerated charge I stead of one at rest.

(Be aware, however, that you still will find a problem if you try calculating the exact speed of the electromagnetic radiation relative to the two observers using classical physics. That's why we need special relativity)
 

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