Answer
See work below.
Work Step by Step
The power lost in a transmission line is proportional to the square of the current. Therefore one wants to use the smallest currents, which means that the transmission voltage should be high.
Take a look at Problem 83. The equation stated in the problem shows that a higher transmission voltage results in lower power loss. Typically, power is transmitted at greater than a hundred thousand volts.
So why choose AC over DC? Using a transformer, it is much easier/cheaper to step the AC voltage down to the safe level (120V or 240V) at the residence or business that ultimately buys the power.
