To send power far, which current wins?

That time, that place

In 1880s America electricity became a product. Edison had built direct-current stations and wiring, with investment and patents already committed.

The problem was distance. DC was hard to change in voltage, so power faded a kilometre or two from the station. Every district needed its own plant.

Why this question

The alternating current pushed by Tesla and Westinghouse reverses direction constantly. Awkward-looking, but with one decisive advantage: a transformer can raise and lower its voltage at will.

Raise the voltage and the same power travels as far less current, and the heat lost in the wire falls with the square of the current. Send it high, then step it down on arrival.

What was found

The fight did not stay technical. Edison's side staged public electrocutions of animals to show AC was dangerous, and pushed for AC in the electric chair.

The verdict came with the 1893 Chicago World's Fair lighting contract and the 1895 Niagara station. Both went to AC, and Niagara's power reached Buffalo thirty-five kilometres away.

That is why the socket in your wall is alternating. Though for very long high-voltage links, direct current is used again today — so neither side lost entirely.