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Sdtootle is offline
Dec24-12, 10:24 PM
P: 17
I recommend reading up Amperes law especially the differential form

Quote Quote by DiracPool View Post
If we use the right hand rule, we see that a hole current, or positive ion flow, creates a magnetic field around the wire where the flux moves in a clockwise direction. Counteractively, electron flow through a wire produces a magnetic flux that flows counterclockwise over the wire. Three questions:

1. Do I have this right?
2. Why on earth would a positive charge cause a circular flux in one direction whereas a negative charge cause one in the opposite direction? Is there some characteristic of the EM field that is responsible for this?
EM field theory is taught with the standardization of how Positive (commonly) charges are effected in a given scenario. The induced magnetic field due to a current carrying wire depends not only the charge of the current (positive vs negative) but also the charge you use as a reference to observe the effects of a magnetic field. If you have a wire with a current of negative charge and utilize a positive charge particle for observation, you will see it getting deflected in the counter clockwise direction. However, if you have a wire with a current of negative charge, but put a negative test particle in the region of the induced magnetic field, it would be clockwise rotation just as you saw with a positive charge current and positive test particle. Positive charge test particles are the usual convention. I hope I didn't miss your true question.

3. Do we get the same effect if the charges are flowing through free space and not a wire? Like cosmic rays or just shooting a beam of electrons through free space?
Once you take a look at amperes law, you'll quickly see that the dependence is on the current density (velocity and density of charges). The wire will effect the mobility of charged particles and depending on where you're measuring your magnetic field, the material can effect the magnetic field as well (magnetic permeability).