What current is needed to transmit 100 MW of power at 200 kV?

1. Average power on an AC line is P_ave = I_rms V_rms. 2. Rearranging for the current gives I_rms = P_ave / V_rms. 3. Write both quantities in base units: 100 MW = 100 x 10^6 W and 200 kV = 200 x 10^3 V. 4. Substitute: I_rms = (100 x 10^6 W) / (200 x 10^3 V). 5. That gives I_rms = 500 A. 6. 4000 A is the current the same 100 MW would need at 25 kV, an eight times lower voltage. 7. 250 A would follow from using 400 kV, so a factor of two slip in the voltage halves the answer. _Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section Why Use AC for Power Distribution?_