Solving for the unknown variable in Motional EMF problem | Physics Homework

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Homework Help Overview

The discussion revolves around a problem related to motional electromotive force (EMF), focusing on determining an unknown variable within the context of the problem presented. The original poster shares their attempts at deriving relationships involving current, magnetic flux, and velocity.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to relate EMF to current and magnetic flux, questioning their assumptions about the direction of current flow and the implications of Lenz's Law. They express uncertainty about their approach and seek validation of their reasoning.

Discussion Status

Participants are exploring various interpretations of the problem, particularly regarding the direction of current and the relationship between velocity and other variables. Some guidance has been offered, but there is no explicit consensus on the correctness of the original poster's approach.

Contextual Notes

There is a mention of assumptions regarding the direction of current flow and the need for confidence in the reasoning process. The problem context includes the application of Lenz's Law and the relationship between speed and other parameters.

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Homework Statement



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The Attempt at a Solution


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\varepsilon = IR

\varepsilon = -\frac{d \Phi}{dt}

\Phi = BA

-\frac{d \Phi}{dt} = -Bl\frac{dx}{dt} = -Blv

So

\frac{-Blv}{R} = I

\frac{-IR}{Bl} = v

Now I plug in and solve, is that right or did I underestimated this question completely?
 
Last edited by a moderator:
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Actually I just realize I assumed the current is running counter clockwise..
 
Actually never mind, by Lenz' Law the direction is counter clockwise for the current
 
Oh wait it says speed, so

\left | \frac{-lR}{Bl} \right | = |\vec{v}|
 
Please...I need mroe confidence.
 
I'll just trust myself...*crickets*
 
Looks OK.

Your answer?
 
1m/s...
 

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