Is this true about the emf in a closed circular wire?

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Homework Help Overview

The discussion revolves around the concept of electromotive force (emf) in the context of a closed circular wire and the implications of traversing that loop with a battery present. Participants are exploring the definitions and properties of emf, particularly in relation to Kirchhoff's rules and the behavior of electric fields in circuits.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to understand the relationship between the potential difference and the position vectors in a closed circuit. Questions arise about the equality of position vectors and the implications of encountering a battery while traversing the loop.

Discussion Status

The discussion is ongoing, with participants providing insights into the nature of emf and its relationship to circuit elements. Some guidance has been offered regarding the role of the battery in the circuit, but there is no explicit consensus on the interpretations being explored.

Contextual Notes

Some participants mention a lack of familiarity with Kirchhoff's rules, which may affect their understanding of the concepts being discussed. There is also a focus on the definitions of position vectors and their implications in the context of the circuit.

latentcorpse
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the emf is defined as the potential difference between two points \varphi(\vec{r_1})-\varphi(\vec{r_2}).

ok so let's say we make a trip round a closed circular wire with a battery to keep the current flowing then r1=r2 and so no emf has been done - is this true and if so why?
 
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The battery in general produces an emf. r1 does not equal r2 because you hit the battery on your walk around the loop. If r1=r2 you can't fit a battery in there.

I'm guessing you're talking about Kirchoff's rules? If you're talking about why the line integral of the Electric field around a closed path is not identically 0, it's because currents are not static.
 


i don't follow. i haven't covered kirchhoffs rules yet. why does r1 not equal r2, these are just vectors from the origin to the point we're at in the circuit so surely regardless of whether we do a lap or not its still the same position vector from the origin that descirbes the point?
 


When you walk around the loop, you will inevitably hit the battery or emf source. That source is like a discontinuity in your loop...when you "walk" over the emf source you need to add the voltage given off by the emf to your potential difference.
 

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