4c. The War of the Currents: Tesla vs. Edison

In the 1880s, there were two proposed currents for the electrical system: Nikola Tesla’s alternating-current (AC) and Thomas Edison’s direct-current (DC). AC has a rotating current which, in the United States and 42 other countries, rotates at 60 a second (60 Hertz or Hz). The rest of the world uses 50 Hz electricity.

With AC current, transformers can switch the voltage up and down. DC current needs special converter stations to transform voltage levels.

Tesla’s AC current won because it was much easier to deliver power across the transmission system. For example, a town could transport electricity from another town.