Ampere's Law and Infinite Current Sheets

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Homework Help Overview

The discussion revolves around applying Ampere's Law to a problem involving infinite current sheets. Participants are exploring the implications of the enclosed current in relation to the magnetic field generated by the sheets.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the interpretation of "enclosed" current in the context of the problem. There is a discussion about whether the Amperian loop should enclose half or a quarter of the current sheet and the implications of this on the calculated magnetic field.

Discussion Status

There is an ongoing exploration of different interpretations regarding the Amperian loop and the current it encloses. Some participants are providing hints and clarifications, but there is no explicit consensus on the correct approach yet.

Contextual Notes

Participants are navigating the constraints of symmetry in the problem setup and how it affects the application of Ampere's Law. The original poster is also referencing an answer key that suggests a coefficient adjustment, which is prompting further inquiry into the assumptions made in their solution.

theBEAST
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Homework Statement


Here is the question:
http://dl.dropbox.com/u/64325990/HW%20Pictures/infinite%20current%20sheet.PNG

Homework Equations


∫B(dot)dl = μoIencl

The Attempt at a Solution


Here is my attempt:
http://dl.dropbox.com/u/64325990/HW%20Pictures/Photo%202012-04-06%2010%2045%2008%20PM.jpg

According to the answer key my answer too large. The answer key has a coefficient of 1/2 in front of my answer... What did I do wrong? For my solution there is magnetic field in the sheet so the path is just L.
 
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hi theBEAST! :smile:

hint: what does "enclosed" mean? :wink:​
 
tiny-tim said:
hi theBEAST! :smile:

hint: what does "enclosed" mean? :wink:​

OH so only half of the current is in that loop right?

Edit: Wait a second... What if my loop only enclosed 1/4 of the sheet so would my answer have a coefficient of 1/4 in front of it? Or would this not be legal as the amperian path is no longer symmetric?
 
theBEAST said:
OH so only half of the current is in that loop right?

no!

the current has to be in the loop, so you need the loop to be both above and below the current

(you're probably thinking of electric cases where one side of a gaussian loop goes through a conductor :wink:)
 

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