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Thread: Question about magnetism.

  1. #1 Question about magnetism. 
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    Hello guys! This is my first post so I figured I would start of with a two questions I need to know for a personal project I am working on so here it goes:
    1) When two like poles on a magnet face each other they repel, does this create work between the two magnets?
    2) When magnets are fixed onto the side of two circular objects with like poles facing up (it doesn't really matter what type) and a iron rod is placed in between the circular objects the magnets will be attracted to that rod and at the same time repel one another causing the circular objects to spin. Does this create work?

    Thank you guys


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  3. #2  
    Moderator Moderator Janus's Avatar
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    Quote Originally Posted by GuessWho View Post
    Hello guys! This is my first post so I figured I would start of with a two questions I need to know for a personal project I am working on so here it goes:
    1) When two like poles on a magnet face each other they repel, does this create work between the two magnets?
    If you let the magnets push each other apart, then yes you can get energy from this, however it will not be more than the work you had to expend to push the magnets together in the first place. If the magnet are held stationary to each other, no work is created.

    2) When magnets are fixed onto the side of two circular objects with like poles facing up (it doesn't really matter what type) and a iron rod is placed in between the circular objects the magnets will be attracted to that rod and at the same time repel one another causing the circular objects to spin. Does this create work?
    I'm not exactly sure of what you are describing, but i can tell you this: No arrangement of permanent magnets are going to allow you to make something that will spin on its own and generate work.


    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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  4. #3  
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    Quote Originally Posted by Janus View Post
    Quote Originally Posted by GuessWho View Post
    Hello guys! This is my first post so I figured I would start of with a two questions I need to know for a personal project I am working on so here it goes:
    1) When two like poles on a magnet face each other they repel, does this create work between the two magnets?
    If you let the magnets push each other apart, then yes you can get energy from this, however it will not be more than the work you had to expend to push the magnets together in the first place. If the magnet are held stationary to each other, no work is created.

    2) When magnets are fixed onto the side of two circular objects with like poles facing up (it doesn't really matter what type) and a iron rod is placed in between the circular objects the magnets will be attracted to that rod and at the same time repel one another causing the circular objects to spin. Does this create work?
    I'm not exactly sure of what you are describing, but i can tell you this: No arrangement of permanent magnets are going to allow you to make something that will spin on its own and generate work.
    Thanks, hun! (: My question has been answered.
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  5. #4  
    pmb
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    Quote Originally Posted by GuessWho View Post
    Hello guys! This is my first post so I figured I would start of with a two questions I need to know for a personal project I am working on so here it goes:
    1) When two like poles on a magnet face each other they repel, does this create work between the two magnets?
    2) When magnets are fixed onto the side of two circular objects with like poles facing up (it doesn't really matter what type) and a iron rod is placed in between the circular objects the magnets will be attracted to that rod and at the same time repel one another causing the circular objects to spin. Does this create work?

    Thank you guys
    This is extremely tricky since a magnetic field can't do work. There are several articles on the subject in the literature. The iea is that the magnetic force is perpendicular to the velocity of the charge on which the force is acting on. When the value of the work is calculated it is found to be zero. The physics is worked out in classical physics, not quantum, although I image the same result is obtained there as well. A classcialy created magnetic field is created by using loops of charges moving in current loops and those loops are used to model macroscopic magnets. Then the charge argument is applied to those charges. The physics is far from obvious.
    Last edited by pmb; June 3rd, 2012 at 06:13 PM.
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