Right-Hand Rule: Current, Magnetic Field, Force

[homevolend]

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.

 

[rock.freak667]

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.

 

[Apphysicist]

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.

 

[rock.freak667]

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 left hand rule for motors[/URL]

 

[Apphysicist]

Both are the same essentially, but since the OP asked for the force, I thought FLHR would be more appropriate: "[URL left hand rule for motors[/URL]

Hm. You learn something new everyday!

 

[vela]

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.

 

[rock.freak667]

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.

 

[SammyS]

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.

$$\vec{thumb}\times\vec{index}=\vec{tallman}$$