Question

Why is electric power for domestic use in the United States, Canada, and most of the Western

Hemisphere transmitted at very high voltages and stepped down to 120 V by a transformer

near the point of consumption?

Answer 1

Power is given by the product of current and voltage.

So, high voltage means high power but a low passage of current. We know that whenever a current flows through a wire it causes energy loss due to joule's effect. Thereby lower current will have lower transmission loss.

Again resistance of a wire is inversely proportional to the radius of the wire. So lower current means higher resistance which is obtained by thickening the wire. This effectively minimizes longer length of the wire thereby saving metal and hence cost effective.

Now, the high voltage is stepped down because most of the electrical appliances cannot handle such high voltages and will burn out. So, it is stepped down to 120 V by a transformer.