Direction of a Magnetic Field for a Current

I can never remember which hand is which (but them, I am a bit dyslexic). But I think the right hand rule is used to predict the force produced by a current passing through a magnetic field, and the left hand rule predicts the field direction around a current.

The right-hand rule is used with conventional current, and the left-hand rule with electron flow.

Cheers! Rich

I thought the right hand rule applied to determining the direction of B/H. One simply wraps their right-hand around the (imaginary) wire wire with their thumb aimed in the direction of the current. The fingers curl in the proper direction. However, I was looking at a Navy manual on this subject, and it shows as below. What am I missing. Does the Navy have a different standard for current flow than physicists and EEs?

=================== Magnetic lines of force are indicated by the letter H and are called H lines. The direction of the magnetic lines may be determined by use of the left-hand rule for a conductor: If you grasp the conductor in your left hand with the thumb extended in the direction of the current flow, your fingers will point in the direction of the magnetic lines of force.

Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

I think that all the military schools use electron flow, as do a number of trade schools, Heald for sure and many others, I think. It confuses the hell out of people when they get out into the real world.

John

Thanks. I wonder what the Air Force and Army use? :-)

Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Nah. Thirty-odd years ago the USAF taught electron flow but also warned us about "civilian" current. ;>)

Mark L. Fergerson

Electron flow, because we're technicians, not academics. ;-)

Cheers! Rich

Were all the ammeters built backwards?

John

So in the navy, current flows from negative to positive voltages? Is that why they always draw their schematics upside down?

Good quote below. (Interesting. It didn't seem to copy into my post.)

Positive ions and protons have been moving around for a long time now.

John

That's what they do in tubes. The Crookes tube and the CRT are notable examples. ;-) So I can't imagine how anything else flows in the wires (I know! _CHARGE_ flows!), unless there are little recombinant factories at the tube terminals. ;-)

The bipolar transistor was their saving grace, because they finally got hole flow - I can imagine the huge collective sigh of relief when they realized, "Ah! Positive current flows in these things! At last!" ;-D ;-D

But what do you mean "upside down?" Is it just that all of the arrowheads are backwards? ;-)

Cheers! Rich

Guess I should tell Rich next time I've got sodium and hydrogen ions buzzing around in a pot of Cl- + Na+ dissolved in H2O OH- + H+ solvent. ;-)

Or any gas discharge (fluorescent lights, thyratrons, etc.), although those still use a lot of electrons, owing to the pokey, fat ions used.

Tim

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