Five Hand Rule: Identifying Wire Direction

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SUMMARY

The discussion centers on the "Five Hand Rule," which refers to the use of the left and right hand rules for determining the direction of force on a current-carrying wire in a magnetic field. The left hand rule is used for conventional current flow, while the right hand rule is preferred in the U.S. for cross products. Both methods yield the same results, but preferences vary by region and educational background. Participants also humorously compare these rules to cultural differences, such as driving orientations.

PREREQUISITES
  • Understanding of magnetic fields and forces
  • Familiarity with conventional current flow vs. electron flow
  • Knowledge of vector cross products
  • Basic physics principles related to electromagnetism
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  • Study the application of the right hand rule in electromagnetism
  • Explore the differences between conventional current flow and electron flow
  • Learn about vector operations in physics, particularly cross products
  • Investigate regional educational differences in teaching electromagnetism
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Students of physics, educators teaching electromagnetism, and anyone interested in understanding the principles of magnetic fields and current flow.

valerie001
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What is the five hand rule?


I need to know what direction the wire is going to move

[N]

I <--------

 
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Do you mean Left hand rule and right hand rule by any chance?

Wire direction in a magnetic field is given by the Left hand rule.
First finger = field direction
Second finger = current direction
Thumb = force direction.

Make all three fingers perpendicular to each other. If you can't see how to do this, watch an Eminem video!
 
right hand rule

I recommend that you learn to use the right hand rule to find the force on a current-carrying wire in a magnetic field.

Here are two links that may help with the right hand rule:
http://www.physics.brocku.ca/faculty/sternin/120/slides/rh-rule.html
http://physics.syr.edu/courses/video/RightHandRule/

(Sorry, but I don't think that's Eminem doing the demos in the second link. :smile: )
 
Last edited by a moderator:
Doc Al said:
I recommend that you learn to use the right hand rule to find the force on a current-carrying wire in a magnetic field.

Right hand rule?? Don't you mean left hand rule, or do we do this different in the UK?

Left hand rule gives direction of the force on a wire in a magnetic field where the current direction is CONVENTIONAL current flow, not electron flow.

In the case above, the wire moves OUT of the PC screen towards you.
 
Adrian Baker said:
Right hand rule?? Don't you mean left hand rule, or do we do this different in the UK?
Looks like you do it differently. (I'm willing to use f instead of \nu for frequency, but don't mess with my right hand rule! :smile: )
Left hand rule gives direction of the force on a wire in a magnetic field where the current direction is CONVENTIONAL current flow, not electron flow.
So does the right hand rule. I use the right hand rule whenever a cross product is involved. To find the direction of \vec{A}\times\vec{B}, just curl the fingers of the right hand from A to B along the shortest arc. The thumb points in the direction of the cross product. (At least that's the way I do it. Check the second of the links I posted for live action video of the right hand rule in use.)

In the case above, the wire moves OUT of the PC screen towards you.
Apparently the right hand rule and your left hand rule give the same answer. Good thing, I suppose!
 
The left hand and right hand rules are both taught in my school. We are taught to use the right hand rule for finding the directions of protons and the left hand rule for electrons (since the directions are opposite). However, the right hand rule is used primarily since the direction of the curled finger can just be made opposite if the particle is negative and the direction left the same if the particle is positive. They're interchangable methods, just depends on your preference. Here in the US it's standard to use the right hand, however.
 
z-component said:
The left hand and right hand rules are both taught in my school.
Again, a deficit of having never finished high school. I was taught only the left-hand rule. (ie: thumb in direction of current flow puts fingers in direction of magnetic field and vice versa) Jeez, but I love learning new stuff here!
 
This is the LH Rule as we teach it:
 

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Could there be some mysterious connection between the "handrule" and which side of the road you drive on? :biggrin:
 
  • #10
No it doesnt, in the UK we drive on the correct side of the road, whilst you americans drive on the other side just because its the opposite of the english (do to the revolution etc...)
 
  • #11
AcEY said:
No it doesnt, in the UK we drive on the correct side of the road, whilst you americans drive on the other side just because its the opposite of the english (do to the revolution etc...)

Well, that's exactly my "theory" you see...
(left hand side-left hand rule,
right hand side-right hand rule)

Anyway, I thought it was well-known Sweden is not one of the United States of america. :wink:
 
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  • #12
there's the all new (?) screwdriver rule for everyone that gets confused as to which hand is the right one. its the same basic idea, i.e. the thumb and fingers only point in one direction, instead of hand curling somewhere is which way you turn the screwdriver and the thumb direction is analogous to which way the screw you are screwing would go under that kind of rotation.

this is really a difficult explanation of something very simple. and actually clockwise and c-clockwise is inherent if you want to know which way the screw goes, so you don't need to make funny hand symbols as you do it.

oh and this ties in nicely with right tighty - lefty loosey ;)
 
  • #13
T@P said:
this is really a difficult explanation of something very simple. and actually clockwise and c-clockwise is inherent if you want to know which way the screw goes, so you don't need to make funny hand symbols as you do it.

oh and this ties in nicely with right tighty - lefty loosey ;)
That works fine until you run into a left-hand thread and strip the thing.
 
  • #14
Clockwise is confusing too - if you are the clock!

To a clock the hands go anti-clockwise.
 
  • #15
Adrian Baker said:
Clockwise is confusing too - if you are the clock!

To a clock the hands go anti-clockwise.
Not if it's dyslexic.
 

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