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Homework Help: Micrometer reading/area of wire calculation

  1. Jan 11, 2010 #1
    I measured the diameter of a wire and got 0.30. This is in millimeters right?

    How would you calculate the cross sectional area? Is it just Πr²?

    so Π x (0.15x10⁻³ x 0.15x10⁻³)
    = 7.0 x 10⁻⁸m²

    Is this right?
    Last edited: Jan 11, 2010
  2. jcsd
  3. Jan 11, 2010 #2
    Well, it could be 0.30 mm, but without further information it could just as easily be for instance 0.30 cm.

    Assuming that the wire has a circular cross-section, then yes, your approach is right.
  4. Jan 11, 2010 #3


    Staff: Mentor

    What is the exponent on 10 below? It looks like an accent mark, not a number.
    Also, since your units are mm for the wire diameter, I think, why not leave the cross-section area in sq. mm.?
    Last edited: Jan 11, 2010
  5. Jan 11, 2010 #4
    Thanks for the help guys! :)

    I'm pretty sure the diameter was in millimeters.

    In my final answer? 8

    I couldn't fit it all in the answer box, lol. Standard form was the only way :(
  6. Jan 11, 2010 #5


    Staff: Mentor

    Yeah, I meant mm, not cm. I edited these units in my previous post.
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