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Homework Help: Bird on a wire

  1. Apr 14, 2012 #1
    A bird, whose feet are 3cm apart, perches on a bare "High tension" power line carrying a
    current of 720A. If the wire has a resistance of 80μΩ/m, calculate the potential difference between the bird's feet. Do you think the bird will be electrocuted?

    r = p * (L/A)

    I have the problem set up as (8 * 10^-5Ω/m) * (.03m/A). I don't know what to put for the area since the cross section hasn't been given. I am aware that the bird should not be electrocuted since its potential is the same as the wire, so there should be no current.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Apr 14, 2012 #2


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    Staff: Mentor

    Hi Wnt2bsleepin, Welcome to Physics Forums.

    Note that the resistivity of the wire is given to you in units of Ohms per-meter. So the cross sectional area is already factored in.
  4. Apr 15, 2012 #3
    Thanks, then all I have to do is multiply by the distance and I should get what I want.
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