Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Power in delevering electricity to a factory

  1. Jul 12, 2005 #1
    A power station delivers 513kW of power to a factory through wires of total resistance of 2.72Ohm. How much less power is wasted if the electricity is delivered at 45200V rather than 13900V?

    I have no idea where to even begin except that I should find the intial current which is found by equation P=I^2R

    Please help me!
  2. jcsd
  3. Jul 12, 2005 #2
    you can also use the fact of p = I^2R = V^2 / R
  4. Jul 13, 2005 #3


    User Avatar
    Science Advisor
    Homework Helper

    Voltage is equal to: V=IR

    So, if the power is equal to [tex]P=RI^2[/tex], then it's also equal to [tex]P=VI[/tex]

    The current being delivered to the circuit comes from the Power and Voltage relationsip.

    To find how much power is lost, you have a new problem that uses the result of the first (you had to solve for I). You use the [tex]P=RI^2[/tex] to find out how much power is dissipated by the wire.

    Change the value of the voltage and repeat. Compare the two results.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook