Final answer:
High voltages are applied for electrical transmission and distribution systems to reduce power losses, take advantage of economies of scale, and to make it easier to increase and decrease AC voltages.
Step-by-step explanation:
High voltages are applied for electrical transmission and distribution systems for several reasons. First, high voltages can be transmitted with much smaller power losses than low voltages. This is because the power losses in transmission lines are proportional to the square of the current, and by using high voltages, the currents can be reduced.
Second, economies of scale make it cheaper to build a few very large power-generation plants than numerous small ones. This requires sending power long distances, and high voltages are more efficient for transmitting power over long distances with minimal energy losses.
Lastly, it is easier to increase and decrease AC voltages than DC voltages. AC voltage is used in most large power distribution systems due to the convenience of raising and lowering AC voltages for power transmission.