Need help for a prove about magnetic field and magnetic force

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Discussion Overview

The discussion revolves around proving that the vector of the magnetic force cannot be parallel to the plane formed by the particle's velocity vector and the magnetic field vector. The scope includes theoretical reasoning and attempts to establish a proof without relying on the definition of the cross product.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant presents the problem and requests assistance in proving the relationship between the magnetic force, velocity, and magnetic field vectors.
  • Another participant attempts to provide a solution using the definition of the cross product, stating that both the velocity and magnetic field vectors are perpendicular to the magnetic force vector.
  • A different participant challenges the previous approach, emphasizing the need to prove the statement without using the definition of the cross product.
  • Another participant comments on the difficulty of proving such a result without relying on established laws of physics, comparing it to proving the electric force's behavior without invoking Coulomb's Law.

Areas of Agreement / Disagreement

Participants express differing views on how to approach the proof, with some relying on established definitions and others insisting on a proof independent of those definitions. The discussion remains unresolved regarding the method of proof.

Contextual Notes

Participants note the challenge of proving the relationship without invoking the definition of the cross product, indicating a limitation in the assumptions that can be made in the proof.

humanallien
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here is the problem:

prove that the vector of the magnetic force cannot be parallel to the plane that contains the vector of the particle's velocity and magnetic field.

someone please help me to solve this, thanks so much for your time.
 
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humanallien said:
here is the problem:

prove that the vector of the magnetic force cannot be parallel to the plane that contains the vector of the particle's velocity and magnetic field.

someone please help me to solve this, thanks so much for your time.

By definition of cross product you have both

[tex]\vec v \cdot \vec v \times \vec B = 0[/tex]

and

[tex]\vec B \cdot \vec v \times \vec B = 0[/tex]

which say that both [itex]\vec v[/itex] and [itex]\vec B[/itex] are perpendicular to [itex]\vec F = \vec v \times \vec B[/itex].
 
thanks for your advice, but it does not help me with the problem because I have to assume that I do not know the definition of F = v X B for the prove. Therefore, I want to proof that the force vector is NOT parallel to the plane without considering the definition of the croos product
 
Since the fundamental behavior of charged particles interacting with a magnetic field comes only from observation (Thomson, Lorentz, etc.) it would seem unlikely that you could "prove" the result by other means. It would be like attempting to prove the electric force on a charged particle acts parallel to the electric field - without invoking Coulomb's Law. Good luck!
 

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