Calculate Emf of Battery in Figure | Homework Problems and Solutions

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Homework Help Overview

The problem involves calculating the electromotive force (emf) of a battery within a circuit diagram, specifically focusing on the lower left battery. The context is rooted in circuit analysis, particularly applying Kirchhoff's laws.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to determine the emf using the given current and expresses confusion about the starting point. Some participants suggest labeling currents and applying Kirchhoff's laws to set up equations. Others provide specific equations but question the correctness of the calculations.

Discussion Status

The discussion is ongoing, with participants exploring different approaches to set up the equations needed to find the emf. Some guidance has been offered regarding the application of Kirchhoff's laws, but there is no explicit consensus on the correct method or solution yet.

Contextual Notes

There is a mention of constraints such as the need to consider the polarities of voltage sources and the limited number of attempts the original poster has to submit the correct answer.

DrMcDreamy
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Homework Statement



What is the emf E of the battery at the lower left in the figure? Answer in units of V.


http://img508.imageshack.us/img508/6/82852928.png



Can someone guide me? I'm confused as to where to start. I think I am supposed go the route of the loop, but I am given the current as 3.54 A. How would I find the emf from there? TIA
 
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Label all currents. Then, write out Kirchoff's current law for each junction, and Kirchoff's voltage law for each closed loop. That should give you the right number of equations to solve for the emf.
 


So would it be:

\epsilon+(1.69x3.54)+(9.34x3.54)+(5.66x3.54)+(1.74x3.54)+11.88v=0
\epsilon=-77.44
 


Okay, that's wrong, I only have one more chance to put in the correct answer, so how would I do this?
 


Write the loop equations for both loops. Watch out for the polarities of the voltage sources. You're given one loop current, so there are still just two unknowns: the second loop's current and the voltage supply value.
 

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