1. The problem statement, all variables and given/known data Ok so i was doing my revision for my exams and i was reading on transformers and they said that stepped-up Voltages and stepped-down currents minimizes for tranformers I^2R power losses in the transmission cable. I know that current is decreased, but a higher voltage, by V^2/R, would also mean a greater power loss? 3. The attempt at a solution I know there have been similar questions like this one below. physicsforums. com/showthread.php?t=227834( theres a space at the .com cause i cant post links yet) But i do not understand their reasoning. For example stewartcs said that problem with this line of reasoning is that P = IV is the power delivered by an electrical energy source not the power dissipated by it. Also the person who asked the question said that he was mixing up the supplied nominal V of the power lines with the V lost by the resistance. i do not really understand what both of them are saying. can anyone explain it to me? thanks!