(V^2/R) / (VI) = (VI) / (RI^2) = V / RI VA = VI = Apparent power W = RI^2 = Real power PF = RI/V = Power factor (V^2/R) / VA = VA / W = V / RI = 1 / PF (V^2/R) = VA^2 / W VA>=W Therefore: V^2/R >= VA !!!! (V^2 / R) * PF = VA VA * PF = W !!!! What is V^2/R? If you have an large inductor, you could have V^2/R with very little current! What causes the magnetic field? Is it "IR^2"? I know that equals joule loss. (real power=joule loss) Efficiency = (??? - Joule loss) / ???? Is it "VI"? I know that equals the electrical power input. (electrical power input>=joule loss) Efficiency = (VI - ???? - Joule loss) / VI Is it "V^2/R"? But this is greater than or equal to electrical power input!!! (V/R>=I) What does this mean when PF<1 ??? Efficiency = ????