right hand rule

Current density has a direction, so the resulting magnetic field has the same symmetry as the current that produces it.

Maxwell's equations are completely symmetrical between E and H (though units often differ, leading to numerical factors in the field strengths). The difference in field behaviour is entirely due to the existence of electric charges and nonexistence of magnetic charges (monopoles).

If magnetic monopoles existed, a steady current of magnetic monopoles would produce an E field looping round the current, just like the H field due to a steady electric current.

The mystery is why there are no magnetic monopoles--and the really deep mystery is why there is matter at all, and why it is the way it is. That's a metaphysical rather than scientific question at bottom, however.

Cheers,

Phil Hobbs

Hi,

I was just wondering why the direction of the magnetic field around a current carrying wire follows the right hand rule, and not a left hand rule? It seems a bit unsymmetrical for one direction to be favoured over the other? Any explanation for this? I would have thought that current in a straight wire would induce a symetrical magnetic field.

cheers, Jamie

It's not "a bit unsymmetrical", it's completely unsymmetrical. As others have said, choosing one hand over the other is a matter of convention, like choosing "positive" for one terminal of a battery, and either works as long as you're consistent.

Why is it like that? Nobody knows; it just is.

If Uncle Al's Eotvos experiment gives positive results, we'll know that spacetime (or whatever you call it in affine theories) is "left-handed" at a very fundamental level. If, as suspected, all forces are unifiable then the reason for EM asymmetry may become apparent as a consequence of "left-handed" spacetime.

Mark L. Fergerson

I don't personally see this as a mystery. Why should there be two methods associated with E&M? Magnetic fields are simply electric fields viewed from another reference frame. Electric fields are just the manifestation of photon momentum exchange between charges. So, why should there be magnetic monopoles?

Again I don't see this as a deep mystery either. We only describe something in terms of other somethings. This inherently means that we

Kevin Aylward snipped-for-privacy@anasoft.co.uk

I read in sci.electronics.design that Mark Fergerson wrote (in ) about 'right hand rule', on Thu, 23 Dec 2004:

Please enlarge or give a specific URL to a page in Uncle Al's big web site.

"Jamie Morken" wrote

Here is design screw up number two in electronic conventions.

You sit there with your pencil in your right hand, look at your left and right down the answer. The light comes on and you scramble to correct the mistake as the TA says "Pass your papers forward".

Design screw up #1 was making the electron negative - well, they tried to have it be positive but effed up.

Then there is the changing the direction of the arrow on bipolar transistors and fets and switching polarity again when deciding which is drain and which is source.

Any more?

Naa. While a dynamic H and E field can be changed into the other by looking from another reference, this is not true for static E or H fields. This means a static H field doesn't become a pure E field at "whatever" speed. "Whatever" in this context means anything between minus c and plus c.

Rene

Not really explaining much : If your current happens to have the other charge (positrons) or direction, the H field would go the other way round.

Rene

Worse yet, is that well over 99.999 percent (of an atom or any "thing" else) has *zero* matter!

Oh dear. Of course what I say is correct here.

Of course it can. With all due respect, clearly you haven't studied Relativistic E&M.

Apply the lorentz transform to a static charge, and low and behold a magnetic field appears.

Of course it does. Its fundamental to the Electromagnetic field tenser and Special Relativity. You just need to chose the *correct* reference frame. Please dont even consider debating this.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

Indeed. If the OP would not have mentioned that it was a wire, both left and right hand rules may apply.

An interesting effect occurs in semiconductor material. Here the current might be perceived as free electrons going one direction, or 'holes' moving the other direction. This might at first seem exactly the same. However, when a magnetic field is applied to this conducting material the voltage potential on the 'sides' will be of different polarity, depending on electron or hole carriers. This with current flowing in the same direction (as defined in the flowing from external plus to minus sense)

Joop

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs

Sorry, maybe my post was not too clear. Electrons or holes will both be influenced by the magnetic field to move in a direction (each with their own left/right hand rule applied). This force direction is the same, however the charge buildup is of different polarity. Experiments with this Hall effect show this.

Perhaps this article can explain it better:

Joop

I read in sci.electronics.design that Boris Mohar wrote (in ) about 'right hand rule', on Sat, 25 Dec 2004:

Thank you. It will take me a few minutes to study that. (;-)

It admittedly was quite a while ago. You make me pull up the second edition of JD Jackson again. Give me some time to read the several chapters again.

Rene

One should also note that according to QED, *all* electromagnetic effects are due to the momentum exchange of (virtual) photons. This further illustrates that electric and magnetic fields are essentially the same thing, motion of photons. There is no separate "electric substance* and "magnetic substance". Its all the same stuff.

Kevin Aylward snipped-for-privacy@anasoft.co.uk