An extension cord made of two wires of diameter 0.129 cm (no. 16 copper wire) and of length 2.7 m is connected to an electric heater which draws 15.0 A on a 120V line. How much power is dissipated in the cord? Do I just use P=IV? But that leaves a lot of "extraneous" information. My second thought was to find resistance: R = p (L/A) A = pir^2 = 1.29E-3^2 x pi = 5.23E-6 R = (1.68E-8) x (2.7/5.23E-6) R = .00867 But then I'm not sure what to do from there. Using P=IV I get 1800 W. But then do I have to multiply by length and area?