Magnetic field around a wire


by johann1301
Tags: field, magnetic, wire
johann1301
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#1
Feb27-14, 07:39 AM
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How do you place/define north and south in the magnetic field around a wire with a current running through it?
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jtbell
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#2
Feb27-14, 08:06 AM
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If you mean the direction of the magnetic field, you use the "right hand rule":

http://hyperphysics.phy-astr.gsu.edu...ic/magcur.html
Drakkith
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#3
Feb27-14, 08:08 AM
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You can use the right hand rule: http://en.wikipedia.org/wiki/Right_h...ith_a_rotation

An electric current passes through a straight wire. Here, the thumb points in the direction of the conventional current (from positive to negative), and the fingers point in the direction of the magnetic lines of flux.
The direction of the flux lines points towards north. Note that a single wire has a magnetic field running around it, not through it like a normal magnet. As such, there is no single north or south pole.

dauto
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#4
Feb27-14, 09:32 AM
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Magnetic field around a wire


Quote Quote by Drakkith View Post
The direction of the flux lines points towards north. Note that a single wire has a magnetic field running around it, not through it like a normal magnet. As such, there is no single north or south pole.
The second statement above contradicts the first. How can the flux lines point towards north when there is no north or south pole?

The first statement is actually incorrect. there is no such thing as a north pole or a south pole for the magnetic field of a single wire. You need a solenoid in order to be able to define poles.


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