A question about the right hand rule

In summary, the right hand rule is a property of the magnetic field that is embedded in Maxwell's equations.
  • #1
Srullic
7
0
Hey everyone, I was hoping you could help me solve a little problem. I'm having a little difficulty understanding why the right hand rule works for determining the direction of the magnetic field. I've found a similar question posted here:

https://www.physicsforums.com/threads/why-does-the-right-hand-rule-works.472162/

And I feel that while the answers were insightful, they kind of missed the point of the question, so I'll try to state mine in a way that can be answered in a yes -or-no manner.

Suppose I have an infinately long conductive wire, and I want to determine the magnetic field around it using only maxwell's equations. Suppose I already deduced the strength of the field, and the fact that it is perpendicular to the direction of both the current and the distance from the wire (I know it is possible to do because I have done it).
My question is this: can I deduce, only from maxwell's equations, whether the field will be directed into the plane of the paper or out from it? Or do I have to experimentally place a test charge close to the wire and measure the Lorentz force on it?

In short, is the right hand rule a property of the magnetic field stemming directly from the mathematical description of it, or is it a purely empirical property?
 
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  • #2
Srullic said:
My question is this: can I deduce, only from maxwell's equations, whether the field will be directed into the plane of the paper or out from it?
Yes.
 
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Likes vanhees71
  • #3
Doc Al said:
Yes.
Elaboration please...?
 
  • #4
Srullic said:
I'll try to state mine in a way that can be answered in a yes -or-no manner.
Doc Al said:
Yes.
Srullic said:
Elaboration please...?

Perhaps you could describe in a less "yes-or-no manner" what type of elaboration you are interested in that is not covered in the previous thread and not addressed by the "yes" that it seems that you specifically requested.
 
  • #5
DaleSpam said:
Perhaps you could describe in a less "yes-or-no manner" what type of elaboration you are interested in that is not covered in the previous thread and not addressed by the "yes" that it seems that you specifically requested.
Well I didn't think I would be taken so literally. If I'm writing a long-ass question, I'll expect people to reply me with a thoughtful answer.
What I meant was, if the answer is yes then show me the proof, and if the answer is no then explain why this is not possible.
When I said the question is asked in a yes-or-no manner, I meant that the question has a definitive answer, as opposed to a vague question like 'why does the right hand rule work?'.
 
  • #6
Well, I did give a definitive 'yes or no' answer, as requested.

A more elaborate answer depends on how much you understand about Maxwell's equations, specifically the one referred to as Ampere's Law. All the sign conventions, such as the right hand rule in question, are embedded in the mathematics. I'll just give you a taste.

Applied to your example, that equation can be written as:
[tex]\nabla \times \vec{B} = \mu_{0}\vec{J} [/tex]
or
[tex] \oint \vec{B} \cdot \vec{dr} = \mu_0 \ I_{enclosed}[/tex]
The first version relates the "curl" of the magnetic field to the current. Note that the curl has embedded in it a cross product, which of course implies a right hand rule.

The second version, the integral form, relates a line integral around a closed loop (the "circulation") to the enclosed current. By convention, the orientation and sign of such an integral follows a right hand rule.
 
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Likes vanhees71
  • #7
Heah, I'll admit it was poor wording on my part.
Anyway I think I got it, thanks a lot!
 

FAQ: A question about the right hand rule

1. What is the right hand rule?

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

2. How do you use the right hand rule?

To use the right hand rule, you first need to determine the direction of the current or the direction the charged particle is moving. Then, using your right hand, point your thumb in the direction of the current or the velocity of the particle. Your fingers will then curl in the direction of the magnetic field.

3. What is the difference between the right hand rule and the left hand rule?

The right hand rule is used for determining the direction of a magnetic field in relation to a current or charged particle, while the left hand rule is used for determining the direction of a current or force in relation to a magnetic field. Additionally, the right hand rule is used for positive charges while the left hand rule is used for negative charges.

4. When should I use the right hand rule?

The right hand rule is most commonly used in electromagnetism, specifically in determining the direction of magnetic fields or forces on charged particles. It can also be used in other areas of physics, such as mechanics, to determine the direction of a force on a moving charged particle in a magnetic field.

5. Is the right hand rule always accurate?

The right hand rule is a useful tool for determining the direction of magnetic fields and forces, but it is not always accurate. It assumes that the current or charged particle is moving in a straight line, and in complex situations where this is not the case, the right hand rule may not give an accurate result. Additionally, it does not account for the strength of the magnetic field or the magnitude of the force.

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