Power of a Sine Wave: Formula to Calculate W

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SUMMARY

The power (W) of a sine wave electrical signal is calculated using the formula P = V * I when the voltage and current are in phase, applicable for purely resistive loads. Frequency does not affect power in this scenario, as demonstrated with examples of 100 volts at 60Hz, 120Hz, and 1kHz yielding the same power output. However, in inductive circuits, the relationship becomes complex due to the wave shape and potential skin effect at higher frequencies. For accurate measurements, especially with non-resistive loads, additional tools such as a function generator may be necessary.

PREREQUISITES
  • Understanding of AC power calculations
  • Knowledge of resistive and inductive loads
  • Familiarity with the concept of phase angle in electrical signals
  • Basic principles of waveforms, including sine and square waves
NEXT STEPS
  • Research the skin effect in AC circuits
  • Learn about the impact of wave shape on power in inductive circuits
  • Explore the use of function generators for sine wave production
  • Study the differences between resistive and reactive power
USEFUL FOR

Electrical engineers, physics students, and anyone involved in AC circuit analysis or power calculations will benefit from this discussion.

Jdo300
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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
 
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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.
 
If the voltage and current are in phase (your load is resistive only), then the power is just P = V * I, independent of frequency.
 
berkeman said:
If the voltage and current are in phase (your load is resistive only), then the power is just P = V * I, independent of frequency.

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
 
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.
 
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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