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Magnetic field produced by two side by side wires  when do they cancel? 
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#1
Jan1810, 04:40 PM

P: 62

I know that the magnetic field coming off the wire will be directed in a circle counterclockwise around the wire. So, from what I understand, it would work something like this: Meaning that, at each magnetic field strength B of radius r from one wire there is an equal and opposite value for that coming from the other wire, meaning that they cancel along the radius and the answer is 4. Is this right or wrong? Am I way off the mark, or somewhat close? 


#2
Jan1810, 04:58 PM

P: 61

Your thread is in jeopardy of being deleted for not using the template.
You are way off. [tex]\vec{B_1}+\vec{B_2}=\vec{B}[/tex] Add only what is at a point, not what is on a circle of radius r when they only share a common point 


#3
Jan1810, 05:25 PM

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Greywolfe1982  Remember to do the vector addition. draw the vector addition at several points along that midline SS'. You get the direction for each B vector component from the counterclockwise rotation direction, and the magnitude falls off as what? 


#4
Jan1810, 05:55 PM

P: 62

Magnetic field produced by two side by side wires  when do they cancel?
And what do you mean "along that midline SS'" Wouldn't doing vector addition (assuming you use vectors from the same point on the circle, say both on the middleright or middleleft) give a vector going in one direction that is twice the magnitude of B_{1} or B_{2}? 


#5
Jan1810, 06:02 PM

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P: 40,639

Then think about all the other points in that 2D plane of the paper, and what the magnitudes and directions of the two contributing B field vectors will look like, and hence what the result of adding them will be. Does that help you to see the answer to the question? 


#6
Jan1810, 06:35 PM

P: 62

I apologize for being so braindead tonight, I feel as if I should know this but I'm lost right now.
So I think that adding two vectors would look like this: The filled dot being the middle, and the other being a distance d from the middle. The vectors added produce a triangle, but I don't see anything notable about it. 


#7
Jan1810, 06:43 PM

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#8
Jan1810, 07:00 PM

P: 62

I take it this is what you meant? The vertical components cancel, but you're left with a horizontal component. At any point, wouldn't the addition of vectors leave you with either a horizontal or vertical component (or both)? 


#9
Jan1810, 07:34 PM

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Now are you ready to answer the original question? 


#10
Jan1810, 07:48 PM

P: 62

I'm thinking of two answers right now, but the one that makes the most sense to me is 1.  at all points along the line connecting the wires. The magnetic fields would be two vertical components of the same magnitude and opposite direction, canceling each other out.



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