I) An energy plant produces an output potential of 7300 kV and serves a city 180 km away. A high-voltage transmission line carries 1190 A to the city. The effective resistance of a transmission line [wire(s)] is 3.78 Ω/km times the distance from the plant to the city. What is the potential provided to the city, i.e., at the end of the transmission line? Answer in units of kV. II) How much power is dissipated due to resistive losses in the transmission line? Answer in units of W. III) Assume the plant charges $ 0.081 /kW · hr for electric energy. At this rate, how much does it cost to transmit energy to the city (by the transmission line heating the atmosphere) each hour? Answer in units of dollars/hr. IV) Consider the money lost by the transmission line heating the atmosphere each hour. Assume the energy plant produces the same amount of power; however, the output electric potential of the energy plant is 20% greater. How much money per hour is saved by increasing the electric potential of the power plant? Answer in units of dollars/hr.
P=IV, so new V=> P/(1.2V)=I/(1.2), so you get I/1.2 now. P=I^2/R, so new P=(I^2)/(1.44R), and R is constant. That new P is multiplied by the money value after being converted to kW, and this new value is subtracted from the money value over in part 3.