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Homework Help: A nail is placed inside an electromagnet, why do we feel a buzzing sensation?

  1. Jan 28, 2010 #1
    1. The problem statement, all variables and given/known data

    A nail is placed inside an electromagnet, why do we feel a buzzing sensation?
    2. Relevant equations



    3. The attempt at a solution
    Is it because of resonance? Can someone please explain? Thanks!
     
  2. jcsd
  3. Jan 28, 2010 #2

    berkeman

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    It depends on the electromagnet. What causes the force of an electromagnet? What creates that force?
     
  4. Jan 28, 2010 #3
    Hi thanks for your reply. I understand that the force is created by the magnetic field due to the current. However, the nail is this case is placed inside the electromagnet, I'm not sure why then there will be a buzzing (vibrating) feeling. Can you elaborate on that a bit more please? Thanks!
     
  5. Jan 28, 2010 #4

    berkeman

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    Correct that the magnetic force comes from the current. What are the two options for that current?
     
  6. Jan 28, 2010 #5
    you mean that the current reverses direction? I can't really see why...
     
  7. Jan 28, 2010 #6

    berkeman

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    What's the difference in the current in a flashlight bulb versus a lightbulb plugged into the wall socket?
     
  8. Jan 28, 2010 #7
    the former is dc and the latter ac. you mean the current changes direction inside the electromagnet? the current source I used was a dc one, though
     
  9. Jan 28, 2010 #8

    berkeman

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    The nail buzzed inside of a DC electromagnet? That's unexpected. Are you sure it was a good DC source, and not going into a pulsating current limit or something? AFAIK, a DC electromagnet should act just like a permanent magnet.
     
  10. Jan 28, 2010 #9
    this is for sure that we're gonna feel a buzzing sensation when a metal bar is placed inside an electromagnet, since this is what the question states. But the whole thing really confuses me. What is placed "inside" an electromagnet... the centre of the electromagnet is a solid iron bar, the best we can do is to place a nail near that electromagnet. But thanks anyway for your help.
     
  11. Jan 28, 2010 #10

    berkeman

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    When you said "inside", I assumed the electromagnet was C-shaped or similar, with a gap in the magnetic path. If it's just a bar, then yes, thre is no inside, just near the ends.

    Update us after you try the experiment. If you do feel a buzzing, and the current source is supposedly DC, I'd suggest using a current meter or voltmeter to check that the current doesn't have an AC component for some reason.
     
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