Motional EMF (direction of moving bar)

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Homework Help Overview

The discussion revolves around understanding the direction of velocity for a conducting bar that is inducing a current in the presence of a magnetic field. The context involves concepts from electromagnetism, specifically motional electromotive force (emf) and the forces acting on a conducting wire.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore different equations to describe the forces acting on the conducting bar, questioning the relationship between the magnetic force and the direction of motion. There is also a discussion on the conditions for steady state and the implications of opposing forces in the context of induced current.

Discussion Status

The conversation is ongoing with participants raising questions about the assumptions related to the direction of forces and the behavior of the system in steady state. Some participants suggest alternative approaches to analyze the situation, while others express confusion about the relationship between the magnetic force and the direction of velocity.

Contextual Notes

There are indications of missing information regarding the specific setup of the problem and the definitions of forces involved. Participants are also grappling with the implications of the magnetic force opposing motion, which may not align with their understanding of the system's dynamics.

sandy.bridge
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Homework Statement



Can someone please explain to me how to determine the direction of the veloicty of a bar that is conducting and inducing a current.

Fb=q(VxB)?
 
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Use F = IL x B instead.
 
Consider a conducting wire attached to a small weight. Fg acts to the right, and Fb (due to magnetic field perpendicular) is directed to the left. Say Fb>Fg. If the system is allowed to reach "steady state" why is the motional emf not Fb-Fg and directed to the right?
 
The only reason I am asking is that I read that the magnetic force that develops due to a velocity always has to oppose it... Which doesn't seem like it would always be the case. Especially if there is a current passing through the wire such that it is that force giving it the acceleration.
 

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