I don't know I just started this course and what happened is they offered an ac circuts short course with no prerequisites and actually all but three of us have been in the class under DC circuts for three months now, we are so behind and we really want to understand and it's a ***** when your so uninformed about basic formulas and such, I refuse to give up so, no I don't know what that equation is all the quest wants is how much neat is lost when 120 volts peak is put across a circute with a 500 ohm resister in it and how much is lost in a sine wave or a square wave?