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Homework Help: Resistance problem

  1. Oct 10, 2004 #1
    9 copper wires of length L and diameter d are connected in parallel to form a single composite conductor of resistance R. What must be the diameter of a single copper wire of length L if it is to the the same resistance?

    obviously since copper is the only thing involved i know the resistivity is the same given the same distance

    R=(resistivity)L/(Area)....i believe this formula may help me...not sure
  2. jcsd
  3. Oct 11, 2004 #2
    For parallel combination, [tex]\frac{1}{R_{eq}} = \sum \frac{1}{R_{i}}[/tex] where [tex]R_{i} = \rho \frac{L}{A}[/tex]. Express A as a function of diameter.
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