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Power of a sine wave

  1. Oct 8, 2006 #1
    Hello,

    What is the formula to calculate the power (W) of a sine wave electrical signal traveling through a wire if I know the frequency, voltage, and current?

    Thanks,
    Jason O
     
  2. jcsd
  3. Oct 9, 2006 #2

    NoTime

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    You need to know the phase angle.
    Unless you just want to know how much power the wire is consuming.
    In which case you need R_wire.
     
  4. Oct 9, 2006 #3

    berkeman

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    If the voltage and current are in phase (your load is resistive only), then the power is just P = V * I, independent of frequency.
     
  5. Oct 9, 2006 #4
    So you are saying that a wire carrying 100 volts at 60Hz has the same amount of power as a wire carrying 100 volts at 120Hz or 1kHz (assuming the same load in all three cases)? I heard somewhere that if you double the frequency of the wave, that the power is 4 times as much, is that true?

    Thanks,
    Jason O
     
  6. Oct 9, 2006 #5

    NoTime

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    No, it's not.
    Wave shape will make a difference in power.
    Frequency only becomes important (if the load is resistive) as it gets high enough for the skin effect to make a significant contributation.

    Since you seem primarily interested in coils then note that P=V * I does not apply to what you are doing.
     
  7. Oct 9, 2006 #6

    es1

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  8. Oct 9, 2006 #7

    es1

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  9. Oct 9, 2006 #8

    NoTime

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    Nice pages es1.
    Since the OP seems to be contemplating square waves the page 2 doesn't really apply to him.

    A square wave reflects the sum of a large number of
    different frequency sine waves.
    This can be tricky in inductive circuits.

    Perhaps Jdo should coinsider geting a function genenerator that can produce sine waves.
     
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