hello all just studying to that crazy electrical engineering 2 exam coming up friday encountered something weird about power dissipation. Given is an AC circuit, source of 10V f=100Hz Z=20 Ohm Matched to give maximum power is the load impedance which will be 20 Ohm as well. now my problem: I have assumed to calculate the current (10V/40 Ohm = 0.25A) and then easily apply I^2*V which gave 1.25W now, in the answer sheet is given solution just half of it : 625mW now ... why did they divide it by two? how should I know when to do that ? is that a different method I should apply for DC / AC circuits ? does it make any difference that it is called impedance and not ressistance Thank you all for you time people Greets, Amit.