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Magnetic Field

  1. Oct 15, 2006 #1
    Why does the north pole of a magnet attract to the north geographic pole of the Earth?
     
  2. jcsd
  3. Oct 15, 2006 #2

    Danger

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    Two things about that...
    #1) it doesn't
    #2) it doesn't

    There might be a third one that I'm missing, but that about covers it.

    To start with, it is not the geographic north pole that it points to; it's the north magnetic pole, which actually moves around. An air traffic controller, for instance, might instruct a pilot to "steer one four seven magnetic" to make sure that the direction isn't taken to mean "one four seven true". The latitude determines how much difference there is between the two poles.
    Secondly, the pole of the magnet is called 'north' because that's the magnetic pole that it points to. It's actually a 'south' pole in reference to the planet.
    Welcome to PF, by the way.
     
    Last edited: Oct 15, 2006
  4. Oct 15, 2006 #3
    it does
    it does

    it does attract to the magnetic SOUTH pole wich is about at the noth geographic pole
     
  5. Oct 15, 2006 #4

    Danger

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    Let's not get into semantics here. Before anyone knew anything about geology or planetology or anything else, people noticed that a lodestone would tend to orient itself toward the 'top' and 'bottom' of the planet. The direction 'north' was already established, so they called the pole of the magnet 'north' since it pointed that way. The planet has more right to the name 'north' than does any magnet.
     
  6. Oct 15, 2006 #5
    the magnetic poles were decieded what is north and south according to where it was pointing on the planet, not the other way around
     
  7. Oct 15, 2006 #6

    Danger

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  8. Oct 15, 2006 #7

    Gokul43201

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    Danger, I was taught that the NP of a magnet points to the Magnetic South Pole, which is very close to the Geographic North Pole. I believe that's how the naming convention works...but it's possible there's more than one convention in use.

    Irrespective of the semantics, reason for this is in the equation for the torque acting on a magnetic moment in an external magnetic field (or, alternatively, in the energy equation).
     
    Last edited: Oct 15, 2006
  9. Oct 15, 2006 #8
    thats how it was decieded, the point that points to the north is the northpole of the magnet, and the otehr southpole. and as science figured out north attract to south tehrefor magnetic south have to be at geographic north
     
  10. Oct 15, 2006 #9

    Danger

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    Gokul, I don't have a clue of who you are other than the fact that I have immense respect and appreciation for your inputs to PF. I've learned a lot from you, and am apparently still doing so in this thread. Because of your expertise and mature approach to everything, I had assumed that you were somewhere in my age range. This is apparently wrong. When I was in school a couple of years ago :uhh: , we were taught it as I posted. It would seem that the convention has changed, so I apologize for the bad posts. And thank you for translating, because I was honestly having some trouble following part of the thread.
     
  11. Oct 17, 2006 #10

    Danger

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    It's now a moot point, but I just remembered something about the way we were taught it. It was based upon the fact that with original lodestone, and the compasses manufactured thereof, the end of the needle was not called the 'north pole'; it was called the 'north-seeking pole'. By that convention, the planetary pole was already defined as 'north'.
     
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