aaron_do
|
Hi,
please note that I said average(V x I) not average(V) x average(I). If V and I are in phase, then average(V x I) will give the same result as rms(V) x rms(I). This would be the case of a sinusoid voltage across a resistor, for example. If you have a capacitor on the other hand, we know from theory that no net power will be transferred to the capacitor as the current and voltage will be 90 degrees out of phase. If you take rms(V) x rms(I) in this case, you would get the wrong result since you have removed the phase information from the V and I before multiplication.
From the opposite perspective, if you take a sinusoid voltage across a resistor, and you try and find the power as average(V) x average(I), you will get zero, which we know from theory is the wrong result.
If you want a deeper understanding of the definition of power, then you will need to revise your electrostatics classes...
Aaron
|