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Question about Circuit element in pencil sharpener

  1. Mar 16, 2009 #1
    Hey guys I'm dissecting this pencil sharpener to see how it works. I understand every component except one. The sharpener is battery operated, running on 4 AA's and once the current leaves the battery you can trace the wire to a small platform containing two elements connected. The first element is the one I don't understand current travels directly to it through a red wire, it is one small strip of metal that is slanted with a gap between it and the strip of metal in the second element. My theory is that as the current flows into the first element electrons build on the end magnetizing it causing it to be attracted to the other part and connecting them, thus completing the circuit. It seems like it would work I just don't understand why you would have to do that, the next element is similar type switch with a gap, this one appears to be activated when the pencil pushes down on the device though.
    Is my theory for the first component close? Do you guys have an idea. I'll try to draw a picture I know it would help understand my question.

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  2. jcsd
  3. Mar 21, 2009 #2
    Maybe a picture of the device would make it a little easier.
  4. Mar 21, 2009 #3


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    No, it would take a LOT of voltage to get enough charge to bend a metal plate. And before that happens, you'd get arcing as electrons simply fly across the air between the plates.

    My first guess was that the pencil would push the metal plates together, but you have already found another plate pair where that happens.

    Is it possible that there are two plate pairs that the pencil must contact?

    p.s. welcome to PF :smile:
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