Magnetic fields and charged particles

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SUMMARY

A charged particle experiences a force defined by F = qV x B, indicating that no force acts when the particle's velocity is zero. The discussion clarifies that if the magnetic field is changing or moving relative to a stationary charge, the kinetic energy of the particle can indeed change. This phenomenon is directly related to Maxwell-Faraday's law, which states that a time-varying magnetic field induces an electric field. The equations F = qE and ∮E.dl = -(d/dt)∫∫B.dS are essential when considering the particle's frame of reference.

PREREQUISITES
  • Understanding of electromagnetic theory, specifically Maxwell's equations.
  • Familiarity with the Lorentz force law (F = qV x B).
  • Knowledge of electric fields and their relation to magnetic fields.
  • Basic concepts of induction, particularly Faraday's law of induction.
NEXT STEPS
  • Study Maxwell-Faraday's law in detail to understand its implications on electric fields.
  • Explore the Lorentz force law and its applications in various reference frames.
  • Investigate the principles of electromagnetic induction and its practical applications.
  • Learn about the relationship between electric and magnetic fields in dynamic systems.
USEFUL FOR

Physicists, electrical engineers, and students studying electromagnetism who seek to deepen their understanding of the interactions between charged particles and magnetic fields.

Sefrez
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It has been stated that a charged particle in the vicinity of a magnetic field experiences a force given by F = qV x B, which states that there is no force when its velocity is zero. It also shows that only the particles direction can be changed, not its kinetic energy.

My question is this: what if you take the frame of reference that the particle has zero velocity and the magnetic field is moving (or changing)? Or simply, you have a stationary charge and pass a magnetic field by it?

In this context, is the kinetic energy of the particle then changed?

If so, is this at all related to, or the base idea of induction?
 
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When you use F=qv×B this equation, v must be in reference to a non-changing B. If you want to use the reference frame in which the particle is the center of coordinates (ie. v=0), then you must use the induction laws, specifically:

E.dl = -(d/dt)∫∫B.dS, and F=qE

PS. It's so much easier to just use F=qv×B.
 
Last edited:

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