Original Tesla induction motor, 1887-1888.

UNITED STATES - AUGUST 29: Nikola Tesla (1856-1943), naturalised American physicist and electrical engineer, was born in Croatia to Serbian parents. Tesla patented in 1887-1888 what has become the most widely used type of electric motor, the induction motor. The induction motor is simple to make because it has no electrical contacts to the rotor. Instead it uses a rotating magnetic field produced by two or more alternating currents in the stationary outer windings (the stator). The induction motor was a major factor in the adoption of alternating current (ac) electricity supplies. (Photo by SSPL/Getty Images)