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Homework Help: Calculate the resistance of iron if

  1. May 9, 2008 #1
    1. The problem statement, all variables and given/known data
    A rectangle bar of iron is [tex]2cm[/tex] by [tex]2cm[/tex] in cross section. Calculate its resistance if the resistivity of iron is [tex]11 \times 10^{-8}\Omega{m}[/tex].

    2. Relevant equations

    [tex]R = \frac{Pl}{A}[/tex]

    3. The attempt at a solution

    [tex]R = \frac{Pl}{A}[/tex]

    [tex]A = 2 \times 2 \times 10^-4 = 4 \times 10^{-4}m[/tex]
    [tex]P = 11 \times 10^{-8}\Omega{m}[/tex]

    How is it possible to find the resistance If I don't have the length?
  2. jcsd
  3. May 9, 2008 #2


    User Avatar
    Homework Helper
    Gold Member

    It isn't.

    Maybe they are looking for the resistance per unit length:

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