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Magnet question

  1. May 5, 2007 #1
    Sorry if this is a fundamental property or not, but I'm curious as hell. Today in class my proffesor had two identical iron rods. Same in weight and length. However, one is magnetic, and the other is not. He said, "You have the two rods and use of your brain. How do you find out which is the magnetic one?"
    That means without suspending them to see which turns towards N/S. Or any other means, like a compass. etc.

    Thanks in advance.
    Last edited: May 5, 2007
  2. jcsd
  3. May 5, 2007 #2


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    Break (or cut) both in half, and what do you think should happen?
  4. May 5, 2007 #3
    I think that the catch is to see if the extremity of one of the rods attires the midpoint of the other. If it does it is magnetized. If not, the other must attire the midpoint of the first.
  5. May 5, 2007 #4
    How would you break a solid iron rod in half with your bare hands?

    lpfr, think you can further explain? Sorry... =\

    How would you be able to tell which attires which? They're completely identical in apperance.
  6. May 5, 2007 #5
    Magnets sometimes feel weird as soon as you pick them up.
    i.e. It's possible you can sense the pull of the earth's magnetic field just holding one in your hand.

    and what lpfr said, the ends suck more than the middle is probably the right answer.
    Last edited: May 5, 2007
  7. May 5, 2007 #6
    A magnetized rod attires iron stronger near its extremities and not at all near the middle. When you put near two extremities there will be one which will attire the other. But when you put a bit of iron near the middle of a magnet rod it will not be attired. Then, if there is any force between the extremity of a rod and the middle of the other, it is the extremity which is magnetized.
  8. May 6, 2007 #7
    I completely understand what you're saying lpfr, but the thing is all i have is the magnet and the rod, but don't know which is the magnet and which is the rod. No iron fillings, nothing like that. Either way, thanks for your answers guys.
  9. May 6, 2007 #8
    I do not think that you completely understood what I said.

    Let's label a rod A and the other B. You put one extremity of rod A near the middle of rod B.
    If you feel an attraction, this means that rod A is magnetized. That's all.
    You can verify putting one extremity of rod B near the middle of rod A. If you feel an attraction, this means that rod B is magnetized.
  10. May 6, 2007 #9
    Ah, thanks alot lpfr.
  11. May 6, 2007 #10


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    A magnet moving at high speeds near a conductor will induce a current due to the changing magnetic flux. Wave both iron bars as fast as possible near your head (without hitting your head, this will negate the results of the experiment). The non-magnetized bar will induce no current within the presumably conductive neurons in the brain. However, the magnetized bar will induce current, resulting in anything from hallucination to memory loss to a mild headache (hence the warning against hitting yourself)
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