| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
28 Jun 2005 10:31:21 PM |
| Object: |
Angular momentum and magnetic field |
Say you have a proton and anti proton that moves at the same speed
toward each other say at 1km/s. Say their path do not make them
collide. Say their path is separated by 1 m spread.
There are 2 forces. The electrical forces will attract the proton and
anti proton together.
Then there is this nice magnetic force. It'll attract the 2 particles
toward the other's path.
Now, the magnetic force doesn't seem to obey conservation of angular
momentum?
Am I wrong here?
Jonathan
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| User: "Old Man" |
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| Title: Re: Angular momentum and magnetic field |
29 Jun 2005 12:58:46 PM |
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<jonathanthio@yahoo.com.sg> wrote in message
news:1120015881.514791.292540@g47g2000cwa.googlegroups.com...
Say you have a proton and anti proton that moves at the same speed
toward each other say at 1km/s. Say their path do not make them
collide. Say their path is separated by 1 m spread.
There are 2 forces. The electrical forces will attract the proton and
anti proton together.
Then there is this nice magnetic force. It'll attract the 2 particles
toward the other's path.
Now, the magnetic force doesn't seem to obey conservation of angular
momentum?
Am I wrong here?
Yes. The angular momentum of an isolated system is always
conserved. As demonstrated in the Feynman Lecture Series,
you may have to include the momentum of the fields which is
proportional to the vector cross product, E x B. Try doing
the problem from different inertial reference frames. A couple
of invariant quantities for the combined electric, E, and
magnetic, B, fields at any point are E^2 - B^2, and the vector
dot product E*B.
[Old Man]
Jonathan
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| User: "" |
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| Title: Re: Angular momentum and magnetic field |
01 Jul 2005 02:25:00 PM |
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Oh so the field itself has momentum, that's explain it.
In another reference where one of the charge doesn't move, we do not
have magnetic force. So we don't have this problem.
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| User: "Uncle Al" |
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| Title: Re: Angular momentum and magnetic field |
29 Jun 2005 12:56:03 PM |
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wrote:
Say you have a proton and anti proton that moves at the same speed
toward each other say at 1km/s. Say their path do not make them
collide. Say their path is separated by 1 m spread.
There are 2 forces. The electrical forces will attract the proton and
anti proton together.
Then there is this nice magnetic force. It'll attract the 2 particles
toward the other's path.
Now, the magnetic force doesn't seem to obey conservation of angular
momentum?
Am I wrong here?
You are wrong. Are you diddling a singlet or triplet state of the
magnetic field?
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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