From: Impedance@UgotOCD.invalid   
      
   There is another factor using perfect sine waves.   
      
   What if the voltage and current are not present at the same time?   
      
   This is called "power factor". Now the power (perfect sine waves for both)   
   becomes E x I x cos(theta).   
   e.g. if you put a voltage across an inductive load and the phase angle lag   
   of the current becomes 30 degrees to the voltage (as a reference) the power   
   factor is 0.866025.   
      
   VA is straight ExI   
      
   RVA (reactive power) is E x I x sin(theta)   
      
   TMI? Onlt power really matters. The rest is wasted in inefficiencies etc...   
      
   For dirty waveforms it can get nuts.   
      
      
   0.707 refers to the RMS value. This is the Square Root, of the Mean, of the   
   Squares.   
   Take a sine wave and dissect it at say 4 regular points. If the peak is 100   
   then the points we have are   
   0 deg.  = cos(0)  x  100V   =  0V   
   90 deg. = cos(90) x 100V  =  100V   
   180 deg. = cos(180) x 100V =  0V   
   270 deg. = cos(270)  x 100V = -100V   
      
   Square all the values for 10K + 0 + 10K + 0   
      
   Take the mean 20K / 4 =  5,000   
      
   Take the SRoot(5,000) = 70.71067 Vac RMS.. Look familiar?   
      
      
      
   Back at ya'...have fun!   
   -------------   
      
   "sno"  wrote in message   
   news:4f1fa1d0$0$2611$892e0abb@auth.newsreader.octanews.com...   
      
   When dealing with true sine wave...the equivalent dc voltage is peak ac   
   voltage times .707 (not sure of the number, is what I remember) has been   
   years since I studied and used these formulas..do not remember if normal   
   ac voltmeter reads average or the equivalent voltage..you are correct is   
   more complicated if voltage/current varies...I spent years teaching   
   basic and advanced electronic...which does not mean much..since was many   
   years ago.....   
      
   have fun....sno   
      
   --- SoupGate-Win32 v1.05   
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