Electricity
Tesla's current
Follow the chain from phenomenon and experiment to machines, networks, and infrastructure.
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1820
Current deflects a compass
Hans Christian Ørsted
Ørsted observed that an electric current in a nearby wire deflected a compass needle, tying electricity to magnetism.
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1821
Electromagnetic rotation
Michael Faraday
Faraday built devices in which a current-carrying conductor rotated around a magnet, an early continuous electromagnetic motion.
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1831
Electromagnetic induction
Michael Faraday · Joseph Henry
Faraday systematically demonstrated that changing magnetic conditions induce electric current; Joseph Henry observed related induction effects independently.
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1864–1865
Maxwell identifies light as an electromagnetic wave
James Clerk Maxwell
Maxwell's paper presented an electromagnetic field theory that implied waves traveling at light speed and identified light as an electromagnetic disturbance. His 1873 Treatise was a later synthesis, a separate event.
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1882
Pearl Street central station
Edison Illuminating Company · Thomas Edison · electrical workers and customers
A coal-fired direct-current station supplied a compact district of lower Manhattan with metered electric lighting.
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1885
The ZBD transformer system enables parallel AC distribution
Károly Zipernowsky · Ottó Bláthy · Miksa Déri
Zipernowsky, Bláthy, and Déri developed a closed-core transformer and a parallel-distribution architecture that allowed the system to change AC voltage in practice.
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1886
Stanley demonstrates transformer-based AC distribution
William Stanley
William Stanley's documented operating system showed that transformers could change AC voltage across a practical local distribution network.
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1885–1888
Rotating magnetic fields
Galileo Ferraris · Nikola Tesla
Ferraris and Tesla independently demonstrated ways to create a rotating magnetic field with phased alternating currents.
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1887–1888
Electromagnetic waves demonstrated
Heinrich Hertz
Hertz generated and detected electromagnetic waves in the laboratory, confirming a major implication of Maxwell's theory.
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1888
Tesla's coordinated polyphase patent system
Nikola Tesla
Tesla documented a coordinated architecture for polyphase generation, transmission, and induction motors in a related set of U.S. patents. Filing, patent grant/public issue, and the AIEE presentation remain distinct stages with separate dates.
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1888
Westinghouse licenses Tesla's patents
George Westinghouse · Nikola Tesla · Westinghouse engineers
Westinghouse acquired rights to Tesla's polyphase patents and integrated them into a company already developing transformers, generators, and AC distribution.
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1888–1892
AC–DC system competition and transition
Edison companies · Westinghouse Electric · Thomson-Houston · municipalities and regulators
Firms, engineers, cities, and regulators compared rival AC and DC systems through deployments, safety disputes, commercial decisions, and standards. During this transition, AC became predominant for general transmission without making DC obsolete.
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1891
The Tesla coil
Nikola Tesla
Tesla developed resonant transformers capable of producing very high-frequency, high-voltage alternating currents.
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1893
AC illuminates the Chicago World's Fair
Westinghouse Electric · Nikola Tesla · George Westinghouse · exposition engineers
Westinghouse supplied an extensive alternating-current lighting system for the World's Columbian Exposition, with Tesla participating in public demonstrations.
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1895–1896
Niagara Falls power reaches Buffalo
Niagara Falls Power Company · Westinghouse Electric · General Electric · Edward Dean Adams · Nikola Tesla · George Forbes · project engineers
Large polyphase generators began operating at Niagara Falls, and transmission to Buffalo followed in 1896 through equipment from multiple companies.
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1895–1901
Wireless telegraphy becomes a system
Guglielmo Marconi · Oliver Lodge · Alexander Popov · Jagadish Chandra Bose · Nikola Tesla · radio experimenters
Multiple researchers developed antennas, tuning, detectors, and transmitters; Marconi organized these elements into a commercially deployed wireless telegraph system.
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1901–1906
Wardenclyffe remains incomplete
Nikola Tesla · J. P. Morgan · Stanford White · Wardenclyffe workers
Tesla pursued a large station for wireless communication and power transmission, but financing ended and the tower never became an operational system.
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