How Is the Magnetic Field Oriented Around a Current-Carrying Wire?

[johann1301]

How do you place/define north and south in the magnetic field around a wire with a current running through it?

 

[jtbell]

If you mean the direction of the magnetic field, you use the "right hand rule":

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html

 

[Drakkith]

You can use the right hand rule: http://en.wikipedia.org/wiki/Right_hand_grip_rule#Direction_associated_with_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]

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.

 

[sardar]

The direction of the magnetic field around a wire with a current running through it can be determined using the right-hand rule. If the wire is held in the right hand with the thumb pointing in the direction of the current, the fingers will curl around the wire in the direction of the magnetic field. This means that the north pole of the magnetic field will be in the direction of the curled fingers, and the south pole will be in the opposite direction.

Alternatively, the direction of the magnetic field can also be determined by using a compass. If the compass is placed near the wire, the north pole of the compass needle will point towards the south pole of the magnetic field and vice versa. This can be used to define the north and south poles of the magnetic field around the wire.

It is important to note that the direction of the magnetic field around a wire is circular, with the strength of the field decreasing as you move further away from the wire. Additionally, the direction of the field will reverse if the direction of the current is reversed. Overall, the direction of the magnetic field around a wire can be easily determined and defined using the right-hand rule or a compass, providing a clear understanding of the north and south poles in the magnetic field.