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Homework Help: Graphite, Pencil, and Paper

  1. Sep 30, 2004 #1
    How does the graphite in a pencil leave a mark on a sheet of paper? Any ideas? My answer is due tomorrow, so a clue or answer would be great.

  2. jcsd
  3. Sep 30, 2004 #2
    I would say that the friction is the main cause of the writing. When graphite is pushed down on paper, a force leaves marks on the paper, which would only happen with friction.
  4. Sep 30, 2004 #3
    It is because of the structure of graphite. As graphite is made of Carbon they must bond together. The Carbons form 3 bonds, but carbon should form 4 with each otehr, therefore there is a free electron to move and be put on the paper. Also, as graphite is layers of carbon, some layers come off as well.

    As a pencil is pulled along a piece of paper it leaves the graphite there.

    Hope that helps.

    The Bob (2004 ©)
  5. Sep 30, 2004 #4


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    Friction and shear cause cleaving between loosely bound sheets in the graphite lattice.
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