Direction of a Magnetic Field for a Current

[W. Watson]

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

 

[John Popelish]

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.

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.
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html

 

[John Larkin]

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

The navy uses electron flow, assuming current flows from negative to
positive, and (almost) everybody else uses conventional-current flow,
pos to neg. So they have to use the other hand.

John

 

[Rich Grise, but drunk]

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.
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html

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

Cheers!
Rich

 

[W. Watson]

The navy uses electron flow, assuming current flows from negative to
positive, and (almost) everybody else uses conventional-current flow,
pos to neg. So they have to use the other hand.

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

 

[John Larkin]

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

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

 

[Rich Grise]

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

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

Cheers!
Rich

 

[Mark Fergerson]

On Thu, 05 Jan 2006 12:34:40 GMT, "W. Watson"

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.

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


Mark L. Fergerson

 

[John Larkin]

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

Were all the ammeters built backwards?

John

 

[Bob Monsen]

[quoted text muted]

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

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

--
Regards,
Bob Monsen

"I am turned into a sort of machine for observing facts and grinding
out conclusions."
-- Charles Darwin

 

[W. Watson]

[quoted text muted]

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

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.)

 

[Rich Grise, but drunk]

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

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

 

[John Larkin]

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

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

John

 

[Tim Williams]

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

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