Tesla was born at Smiljan in Croatia, at that time within the Austro–Hungarian empire. He studied mathematics and physics at the University of Graz and philosophy at Prague. In 1884 he emigrated to America where he worked for Thomas Edison for a while before a bitter quarrel led to his resigning and joining the Westinghouse Company. After his invention of the first alternating current (a.c.) motor in 1887 he left to set up his own research laboratory.

Most commercially generated electricity at that time (including that of Edison) was direct current (d.c.). Tesla saw some fundamental weaknesses in the d.c. system: it required a commutator and needed costly maintenance. The main advantage of a.c. was that, with transformers, it was easier and cheaper to transmit very high voltages over long distances. Tesla's invention was soon taken up by Westinghouse and led to intense competition with Edison and the other d.c. users. Edison was not beyond suggesting that a.c. was inherently dangerous and when in 1889 the first criminal was electrocuted, Edison proposed that being ‘westinghoused’ would be a good term to describe death by the electric chair.

In 1891 the transformer was first demonstrated at the Frankfurt fair when it was shown that 25,000 volts (alternating) could be transmitted for 109 miles (175 km) with an efficiency of 77%. The a.c. system soon replaced d.c. electricity, which was confined to specialized uses.