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Power, Current and Voltage

  1. Feb 18, 2015 #1
    Why does electrical power = voltage x current? I understand power is the rate of doing work or the rate of energy transfer but how does that relate to voltage an current?

    I know current is the flow of charge and voltage is a difference in charge between 2 points.
  2. jcsd
  3. Feb 18, 2015 #2
    Because voltage = joules/coulomb and
    current = coulombs/second so

    Voltage * current = joules/second

    Which is the definition of power.
  4. Feb 18, 2015 #3


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    I prefer to state Power dissipated = R*I2. This is correct both for DC and AC.
  5. Feb 18, 2015 #4

    jim hardy

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    er, uh, make that "voltage is a difference in potential"

    Be very rigorous about learning your basic units .
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