# Polarity of the wire

1. Homework Statement
There is a straight current carrying wire. A magnetic field is produced round the wire. Will north pole and south pole be developed?

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Dick
Homework Helper
Where would they be? All magnetic flux lines are closed. What do N and S poles really mean? Questions to ponder.

Where would they be? All magnetic flux lines are closed. What do N and S poles really mean? Questions to ponder.
I think they would be on the opposite sides of the wire. I mean if we cut the cylindrical wire(small diameter) along its diameter, we would get two separate parts of equal length which were north pole and south pole previously. Am I right?

I dont know what north poles and south poles exactly mean.

Dick
Homework Helper
You talk about poles where the magnetic field has the form of a dipole, like a solenoid or a bar magnet (like the earth's magnetic field). If you put a compass on the earth it points towards one pole and away from the other. I get your point about cutting along diameters, but if you follow a compass located near the wire, it will just lead you in circles around the wire, not to any definite region. That's my interpretation anyway.

You talk about poles where the magnetic field has the form of a dipole, like a solenoid or a bar magnet (like the earth's magnetic field). If you put a compass on the earth it points towards one pole and away from the other. I get your point about cutting along diameters, but if you follow a compass located near the wire, it will just lead you in circles around the wire, not to any definite region. That's my interpretation anyway.
Well, I seem to understand your point. You might mean to say that in this case magnetic field exists without any poles at all. But really are you sure that what I said is wrong?? Think of a bar magnet and solenoid. Magnetic field lines are continuos inside the solenoid and I think I am not wrong if I say that it is true for a bar magnt too. What do you think?

Dick