“Intelligent people tend to have less friends than the average person.”
Nikola Tesla
There are two types of electricity, Direct Current (AC) and Alternating Current (AC).
Vastly simplifying, in DC electrical systems the current flows in one direction, like current in a stream. This makes designing certain appliances easier; the motor turns in the direction of the current much like a stream turns a water wheel. Spinning a motor or clicking a telegraph is relatively straightforward.
In AC the current flows both directions. The primary advantage over AC is current can travel much further than DC without a loss of power. However, turning a motor – harnessing the electricity do something useful – is more complicated. A water wheel if the current goes back and forth simultaneously is not all that useful.
Nikola Tesla worked briefly for Edison but quit. Westinghouse, the inventor of air brakes for trains, funded him. Among Tesla’s many inventions is a motor that uses AC electricity. Besides operating from long-distance electrical lines, the Tesla “induction” motors use magnetism and do not require brushes, which DC motors used to harness the electricity. This meant fewer moving parts and less friction, making them more powerful and longer lasting. Additionally, Tesla’s motors did not require inverters and started up immediately.
Almost all electric motors today are induction motors, including those that power electric cars.
Edison and others believed AC-based motors, like induction motors, were impossible.