- #1
Motion of a charged particle in a uniform magnetic field
- Context: Undergrad
- Thread starter bobsmith76
- Start date
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Discussion Overview
The discussion revolves around the motion of a charged particle in a uniform magnetic field, specifically addressing why such a particle moves in a circular path rather than continuing in a straight line. The scope includes conceptual clarification and exploratory reasoning regarding the forces acting on the particle.
Discussion Character
- Exploratory, Conceptual clarification
Main Points Raised
- One participant questions why a charged particle does not continue in a straight line in the absence of other forces, suggesting a need for explanation.
- Another participant proposes that the behavior of particles in a magnetic field may be a brute fact, implying that no further explanation can be provided.
- A different participant points out that the force acting on the particle is always sideways, questioning how the particle could maintain a straight path under such conditions.
- Another participant explains that the sideways force causes the particle to turn, and as it continues to feel this force at various points in its path, it results in circular motion. They reference centripetal force to aid understanding.
- One participant expresses understanding after the explanation, indicating a shift in their perspective.
Areas of Agreement / Disagreement
The discussion contains multiple viewpoints, with some participants expressing uncertainty about the underlying reasons for the particle's motion, while others provide explanations that suggest a consensus on the mechanics involved, though no definitive agreement is reached on the necessity of a deeper explanation.
Contextual Notes
Participants do not fully resolve the question of whether the behavior of charged particles in magnetic fields can be explained or if it is simply a characteristic of their motion. There are assumptions about the nature of forces and motion that remain unexamined.
- #2
bobsmith76
- 336
- 0
ok, I'm starting to think that it's just a brute fact. that's just the way particles behave in a magnetic field and no explanation can be offered.
- #3
tiny-tim
Science Advisor
Homework Helper
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hi bobsmith76! 
but that F force in your diagram is always sideways …
but that F force in your diagram is always sideways …
if you believe the diagram, then how can the particle go straight when there's a sideways force on it? 
- #4
RobinSky
- 112
- 0
Think of it like this, the particle is feeling the force on the side, it makes it turn (but the velocity will not change). So now consider the same particle in a new point in the system, your particle has turned for a little bit, and now still feels the force on it's side, which will make it continue to turn.
Now do this for all following points that exist in it's path, and you will see it will continue to move in a circle.
As the diagram says, the force is always perpendicular to the direction it's moving.
Think of a centripetal force, if that makes it more easy.
Now do this for all following points that exist in it's path, and you will see it will continue to move in a circle.
As the diagram says, the force is always perpendicular to the direction it's moving.
Think of a centripetal force, if that makes it more easy.
- #5
bobsmith76
- 336
- 0
ok, i get it now. thanks.
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