a transmission line that has a resistance per unit length of 4.50 3 1024 v/m is to be used to transmit 5.00 mw across 400 mi (6.44 3 105 m). the output voltage of the source is 4.50 kv. (a) what is the line loss if a transformer is used to step up the voltage to 500 kv? (b) what fraction of the input power is lost to the line under these circumstances? (c) what if? what difficulties would be encountered in attempting to transmit the 5.00 mw at the source voltage of 4.50 kv?