Our teacher taught us about Gauss law of magnetism, $\phi_B=\oint_s{\small{}}\vec {B} .\vec {ds}=0$(being valid because magnetic field line form closed loop, right?) which denies the existence of magnetic monopole.
However, it does not decline the existence of magnet with no pole, and I understood how.
Then he told us that one such example is an toroid.
Question:
But, I am not able to understand why does a toroid have no pole? Shouldn't it have a pole similar to circular loop, why it does not? (Please explain this one in detail.)
Also, while thinking about the above, what about a long current carrying conductor? Does it have a pole or not?
(Sorry for the rudimentary question, but high school physics is always like take this and we get that and things, never explains why? It bothers me.)
Thank you!
Best Answer
A magnetic pole designates an "end" of a magnet. If the magnetic flux through one "face" of the magnet is positive (i.e. the magnetic flux density "comes out" the magnet), this face is called a north pole.
On a toroid, what would be the surfaces where the magnetic flux flows out of the toroid ?