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Quick Current and Resistance problem

  1. Feb 13, 2007 #1
    A problem is "A high-voltage transmission line with a resistance of 0.305 Ω/km carries a current of 1.10 kA. The line is at a potential of 800 kV at the power station and carries the current to a city located 179 km from the power station. What is the power loss due to resistance in the line?".

    So the formulas i have are I^2R=power and (Change in V)^2/R. I just do not know how to put these together to save my life. I'd appreciate any help i can get. Thanks.
  2. jcsd
  3. Feb 13, 2007 #2


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    Staff Emeritus
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    Can you determine the total resistance of the power line?
  4. Feb 13, 2007 #3
    Yup, i got it. Multiply the .305 times 179km, and then just plug that in the I squared R formula. And then you get the power lost. Thanks so much.
  5. Feb 13, 2007 #4


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    Staff: Mentor

    Not so fast there, buckaroo. The 0.305 Ohms/km is the resistance of the wire. There are two lengths of wire 179km long that make up the transmission line. The current has to circulate around the full loop, right? So what distance should you use in your calculation to figure out the total power lost by the current flowing in the wire(s)?
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