Right-Hand Rule: Current, Magnetic Field, Force

In summary, the left hand rule is to point the index finger in the direction of the magnetic field and the middle finger in the direction of the current. The thumb points in the direction of the force.
  • #1
homevolend
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Homework Statement



A wire carries a current from left to right, thru a magnetic field which has direction towards you. What is direction of magnetic force on the wire, draw diagram.

Homework Equations





The Attempt at a Solution




I not sure how to do the right hand rule in this situation, so I am guesing it is to the right, because of the way the current is moving.

Thanks.
 
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  • #2
Since you want the direction of the force, you'd want to use the left hand rule, not the right hand rule.

For the left hand rule, point the index finger in the direction of the magnetic field, then the middle finger in the direction of the current. The thumb will then point towards the direction of the force.
 
  • #3
rock.freak667 said:
Since you want the direction of the force, you'd want to use the left hand rule, not the right hand rule.

For the left hand rule, point the index finger in the direction of the magnetic field, then the middle finger in the direction of the current. The thumb will then point towards the direction of the force.

What? I guess you come up with the same answer and to each his own method, but you would use right-hand-rule since it's still a vector cross-product, whether you think of F=q*vxB or F=l*IxB. In both those ways of thinking about magnetic force, you put your index fingers along the first vector (v or I...the velocity of the charge is in the direction of the current, so they're the same) and curl them into the second vector, B. Then your thumb is in the direction of the force.
 
  • #4
Apphysicist said:
What? I guess you come up with the same answer and to each his own method, but you would use right-hand-rule since it's still a vector cross-product, whether you think of F=q*vxB or F=l*IxB.

Both are the same essentially, but since the OP asked for the force, I thought FLHR would be more appropriate: "[URL [Broken] left hand rule for motors[/URL]
 
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  • #5
rock.freak667 said:
Both are the same essentially, but since the OP asked for the force, I thought FLHR would be more appropriate: "[URL [Broken] left hand rule for motors[/URL]

Hm. You learn something new everyday!
 
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  • #6
Hmm, I don't see the point of that rule. It's basically the same thing using the other hand with the fingers assigned differently. It just seems like one more random thing to memorize rather than understanding the general rule associating the vectors in any cross product with the fingers on the right hand.
 
  • #7
vela said:
Hmm, I don't see the point of that rule. It's basically the same thing using the other hand with the fingers assigned differently. It just seems like one more random thing to memorize rather than understanding the general rule associating the vectors in any cross product with the fingers on the right hand.

Yeah it is the same thing except left you point in the direction of the current and the right gives the direction of the induced current. Depends on convenience I guess.
 
  • #8
I've run into this issue discussed elsewhere. That was the first time I had heard of a left-hand rule.

My take on this is that in physics courses in the U.S.A., we only have right-hand rules. - maybe engineering does otherwise. We write the related equations in terms of the vector product. That always follows the right-hand rule - removing any ambiguity.

[tex]\vec{thumb}\times\vec{index}=\vec{tallman}[/tex]

 

1. What is the right-hand rule?

The right-hand rule is a method used to determine the direction of a force on a moving charged particle in a magnetic field. It is also used to determine the direction of the magnetic field created by a current-carrying wire.

2. How does the right-hand rule work?

The right-hand rule works by using the thumb, index finger, and middle finger of your right hand. The thumb points in the direction of the current, the index finger points in the direction of the magnetic field, and the middle finger points in the direction of the force on the particle.

3. What is the connection between current, magnetic field, and force?

When a charged particle moves through a magnetic field, it experiences a force perpendicular to both the direction of the magnetic field and the direction of the particle's motion. This force is proportional to the strength of the magnetic field and the current of the particle.

4. Can the right-hand rule be used for both positive and negative charges?

Yes, the right-hand rule can be used for both positive and negative charges. The direction of the force will be opposite for negative charges, but the same hand orientation is used.

5. Are there any variations of the right-hand rule?

Yes, there are variations of the right-hand rule depending on the specific situation. For example, for a current-carrying wire, the thumb would point in the direction of the current and the fingers would curl in the direction of the magnetic field. It is important to understand the specific situation in order to use the right-hand rule correctly.

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