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How to find the Current?

  1. Jun 23, 2015 #1
    1. The problem statement, all variables and given/known data
    You are working for the power company and wonder why we use a set voltage of power lines instead of a set current. You test your system on 38 m of aluminium wire with a diameter of 10.0 cm. The resistivity of aluminium is 2.65e-8 Ohm*meters. You place a 9000 Volt potential difference across the wire.
    a. What is the current through the wire?
    b. What is the power lost from the wire?



    2. Relevant equations


    3. The attempt at a solution
    a. First, i need to find the Resistance of the wire by using equation R = pL /A
    p = 2.65 e-8, L = 38 m, A= pi * (.05 m) ^2
    Then i find the Current by I = V / R. I plug in the number, and i keep get the wrong answer.

    For the power lost: Can i use the equation P = I * V ?
     
  2. jcsd
  3. Jun 23, 2015 #2

    gneill

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    Staff: Mentor

    What answers do you get for resistance and current?
    You can, yes. There are also two other forms of power equation that you can use: P = I2R and P = V2/R.
     
  4. Jun 23, 2015 #3
    For the current, i get 70194473.39 A... , R = 1.23e(-4)
     
  5. Jun 23, 2015 #4

    gneill

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    Staff: Mentor

    The values are good for the problem as stated, although you might want to use scientific notation for the current value and show only a reasonable number of significant figures.
     
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