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The distance at which magnet can attract

  1. Aug 4, 2011 #1
    Is it possible for one magnet to attract another over a distance of 1m? To specify, if magnet 1 was at point A on the East side of the ruler, and magnet 2 was stationary at point B on the West side of the ruler. Could magnet 2 attract magnet 1 so much that both were bound together at point B on the West Side of the Ruler?
     
  2. jcsd
  3. Aug 4, 2011 #2

    xts

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    Yes, it is.
     
  4. Aug 4, 2011 #3
    what size of magnet would i need? and would it have to be electromagnetic
     
  5. Aug 4, 2011 #4

    Drakkith

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    Staff: Mentor

    Sure. In fact, assuming the poles are oriented correctly, the magnets already attract each other from any distance. The force of the attraction falls off at a distance though. If you double the distance the attractive force decreases by 4x. So after a bit the force can no longer overcome friction. This is why magnets don't usually go flying across the room to another one.
     
  6. Aug 4, 2011 #5

    xts

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    Ooouch? Are you quite sure that number? Maybe rather 8?
     
  7. Aug 4, 2011 #6

    Drakkith

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    I didn't think so. It falls off with the square root correct? Doubling the distance is 4 times less, quadrupaling the distance would be 16 times less, and etc right?
     
  8. Aug 4, 2011 #7

    phinds

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    Gold Member
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    Put a REALLY big magnet at B and a light one at A :smile:
     
  9. Aug 4, 2011 #8
    So when you have seen in a movie the bad evil guy using his super ultra magneto-gizmo weapon it usually is bad science.
     
  10. Aug 4, 2011 #9

    xts

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    Not quite correct. At larger distances (comparing to magnet size) falls with [itex]1/d^3[/itex]. Doubling the distance makes 8 times smaller force.
    Guess why?
     
  11. Aug 4, 2011 #10

    Drakkith

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    Staff: Mentor

    Ah ok. I must have been thinking in 2d. :biggrin:

    Usually yes. Although it depends on the circumstances in the film.
     
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