Where are the poles of the wire? When current is passed through a copper wire there are circular magnetic field lines around it but where are the north and south poles to that circular magnetic field?
 A: The poles of a magnetic field, like the pot of gold said to be at the end
of the rainbow, can be found by following along the field-line path.  So, if you point
at the magnetic North pole on Earth, and follow that path, you go ... North.
If you examine that field line, however, you'll soon note that it ISN'T 
pointing to Earth's north pole, but rather points down, into the ground.
Dipole magnets (with one N and one S pole) are important, but the
exact point where the field lines come to a point... is just an 
imaginary point.   It's inside the metal of the magnet, or under the
surface of the Earth, and if you DID go there, you'd find the lines
from all directions don't meet.   They just gather ... get close.
From outside the Earth, or outside the  magnet, the magnetic 'poles' give you
some way of understanding the field lines' shape.   Up close, they
are (to the best of our observation) just as illusory as the pot
of gold at the end of the rainbow.
With a straight wire carrying current, the field lines do not
create the illusion of poles.
