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Homework Help: Magentic induction and shielding

  1. Jul 16, 2007 #1
    ps43.gif
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    This happens when the ferro-magnetic material is placed near to the magnet. (call this induced magnetism)

    BUT

    if the bar shape ferro-magnetic material's length is compressed into as thin as a sheet of iron,

    5yv0o6t.jpg

    Electromagnetic shielding occurs.

    --------------------

    In the first situation, an iron pin will be attracted by the induced iron, but in the second situation, the iron pin will not be attracted.

    I do not understand why will there be two occcurance, and how to classify any situation to know which will occur.
     
  2. jcsd
  3. Jul 16, 2007 #2

    HallsofIvy

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    Science Advisor

    What "pin" are you talking about? In the first case you have a bar of iron that is attracted to the magnet. In the second you flatten the iron into a sheet which will also be attracted to the magnet. I see no "pin" in either case.
     
  4. Jul 16, 2007 #3
    the pin is not in the picture
    imagine a pin approach the iron bar, or sheet in both cases, from the right.

    From what i was told, the magnetic field will flow through the iron bar, therefore magnetising it. (so the pin will be attracted to the iron bar)

    But, in the case of a the iron sheet, the magnetic field is diverted(shielding), and anything belhind will not experience magnetism from the magnet. (the pin does not feels any attraction)

    what difference is there between a sheet and a bar magnet? isnt it just the 'length' of that piece of iron? why are there 2 different results?
     
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