Solving Ampere's Law Trouble: My Mistake in Calculating B?

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The discussion revolves around a misunderstanding of Ampere's Law and the calculation of the magnetic field (B) around a current-carrying wire. The original poster questions whether B is constant within a fixed rectangle. User ehild clarifies that while the direction of B changes, its magnitude remains constant in the rectangle. Additionally, ehild explains that for a long straight wire, the magnetic field strength is inversely proportional to the distance from the wire (B is proportional to 1/r). This highlights the importance of correctly applying Ampere's Law in calculations involving magnetic fields.
giladsof
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Where is my mistake? I have a feeling it's in the calculation of B... ?
 
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Do you mean that B is constant inside the rectangle?

ehild
 
It's a given that the rectangle is fixed to the ground..

So apart from the fact that the magnetic field in it changes direction all the time, B's size is constant
 
So you say that the magnetic field of a current carrying wire does not depend on the distance from the wire?

ehild
 
For a long straight wire, B is proportional to 1/r.
 

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