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Homework Help: Electric Circuit Question

  1. Nov 30, 2007 #1
    Hello. Hopefully someone here is able to answer this. I'm not sure if it's easy or hard, but it sure is frustrating... Here is the question...word for word, I would make a sad attempt at a picture, but it would probably be wrong. So...

    "A powerhouse near a waterfall has a large DC generator that produces electricity for a factory 0.50 mile away. The energy is transmitted over two cables each with a resistance of 0.25 Ohms/Mile. Given that the factory requires 45kW at a voltage of 110V to run its equipment, what must be the output of the powerhouse"

    We haven't talked a lot about resistances yet, so I think I'm probably making mistakes there...but yea. Thanks in advance.
  2. jcsd
  3. Nov 30, 2007 #2


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    Staff Emeritus
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    For DC, power P = V * I, so I = P/V.

    The total resistance over the line, R, is given by R = [itex]\rho[/itex] L, where [itex]\rho[/itex] is the resistance per unit length and L is the total length of the line.

    Now what is the voltage drop and power loss over the line?
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