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Homework Help: Electronics Question!

  1. Dec 12, 2004 #1
    Why over long distance power transmissions do we use a high voltage and not a high current?

    I'm curious about this, I have a test tomorrow and totally forgot to ask the teacher for the answer and got a test tomorrow. :bugeye:
    I'd appreciate if someone could help me out here!
  2. jcsd
  3. Dec 13, 2004 #2
    We use high voltage so it's more efficient because current takes up the wires and less wires is good :p

    By wires, I mean cable.. sorry for my crappy english.
  4. Dec 13, 2004 #3
    The heat loss in a resistor (or wire) is given by the equation,

    [tex] P=I^2 R [/tex]

    if you notice, the heat loss (or power loss) is proportional to the current.

    And the reason why we have high voltage is because we have low current with high voltage. This is given by the relation

    [tex] P=VI [/tex]

    Since, because of conservation of energy, there is a fixed amount of electrical energy the generator can produce at a certain instant. Therefore, if you have P as a constant and you will see that voltage is inversely proportional to the current.

    : )
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