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Anonymous Poster

– Forces between two current elements and Newton's third law

09/29/2007 5:22 AM

Forces between two current elements and Newton's third law

Consider two non parallel wires each carrying a current which located at one plane surface.
According to electromagnetic theory, the forces between two straight and solid wires mentioned can be estimated as follow:

F= i . (L x B)

Where the "F" is force vector that applied to each wire and "L" and "B" are current path vector and flux density vector respectively. Also "i" is amount of current and "x" is vector multiply symbol.Therfore the vector of forces are perpendicular to "L" or wires body.
Whereas two wires are not parallel, generally that mentioned forces which applied to wires can not be parallel. As you see we have two piece of material that apply two mutual forces to each other which are not alien and this is inconsistent with Newton's third law seemingly.

What is your opinion?

REGARDS

MSJ

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Anonymous Poster
#1

Re: – Forces between two current elements and Newton's third law

09/30/2007 8:19 AM

According to electrical engineering experience, two free wires carrying currents can not stable non parallel, and applied electromagnetic torque to each wire rotate them and they will be parallel after short time.Therefor in non parallel configuration of wires we need to assume one supplementary mechanical force in system which we were not considered it.

Of course in free wires moving duty we have involved with problem yet. In that condition because of magnetic field variation, the mass of magnetic field change due to wires moving. Therefore the essential principle of survival momentum is fulfilled and we can forget that inconsistent (action and reaction forces) temporarily.

What is your opinion?

REGARDS

MSJ

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Join Date: Jul 2007
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#2

Re: – Forces between two current elements and Newton's third law

09/30/2007 3:57 PM

These are vectors. Use the parallel components.

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