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So why is for example the magnetic field orientated counterclockwise when the electrons are going down in a current wire (or current going up)? Why is the magnetic field not going clockwise, is there a more fundamental reason for?

Probably why-questions are often not appropriate in physics but perhaps sometimes you can ask for deeper causes?!

Marijn
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    This is purely a convention. You could do physics (well, electromagnetism anyway; we're not going to talk about the weak interaction) just as well with using a left-hand rule for all the cross-products because all experimental observable are constructed of an even number of application of such rules. – dmckee --- ex-moderator kitten Oct 06 '16 at 15:33
  • You could similarly ask why the earth is turning counterclockwise when observed from the north pole. Or the galaxy, or... –  Oct 06 '16 at 16:40
  • But the cause of the turning of the earth has probably something to do with the orientation of the accretion disk of our stellarsystem. So my question is not why we call it north or south but what causes it. – Marijn Oct 06 '16 at 18:02
  • Well, nature seems to know difference between left and right somehow, that makes nature to decide the magnetic pole based upon direction of current. – kpv Oct 06 '16 at 18:56
  • @kpv No. We could have named the pole as we do now, adopted the use of left-handed coordinate systems as the default and ended with the same physical description of electromagnetism. It's a convention without physical significance. Weak decay system can tell left-handed coordinate system from right-handed ones, but electromagnetism is blind to the distinction: it is only our labeling of diagrams that cares. – dmckee --- ex-moderator kitten Oct 06 '16 at 22:06

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