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Homework Help: Resistivity of Copper Wire

  1. Mar 18, 2012 #1
    12-gauge copper wire has a radius of 1.03×10−3 m. (a) What is the resistance of 11.5 m of this wire at 20°C. (b) How much current will pass through the wire if a potential difference of 9.00 V is applied across it?
    The resistivity for copper is 1.7E-8 ohm meters
    For part a:
    The equation is R=ρ(L/A) and A=∏r2.
    I solved for Area and got 3.33E-6 m2.
    Then I did R=1.7E-8(11.5/3.33E-6)
    R=.0587 ohms.

    However, when I plug this into the system it says it's wrong. What did I do incorrectly? I double-checked my multiplication and everything.
     
  2. jcsd
  3. Mar 18, 2012 #2
    Never mind, it was sig figs
     
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