|
|
Time-line of "All Things Electric
and Magnetic"
See also timeline of geomagnetism
and of physics, astronomy human society
~ 600 BC ---
Thales of Miletus notices that amber rubbed with dry cloth attracts
light objects
~ 1000 --- Chinese find that a Lodestone floating on a"boat" in a bowl of water always
points north-south.
1600---In "De Magnete", Willliam Gilbert explains the action of the magnetic compass by assuming Earth is a giant magnet. Discovers other features of permanent magnets.
He also names the force observed by Thales "Elektric" force , since "Elektron" is Greek for "amber"
1676 --- Ole Roemer, an astronomer, deduces the approximate velocity of light from systematic changes in the observed orbital periods of a moon of Jupiter. When Earth is approaching Jupiter, the period seems shorter.
1733 --- Charles Dufay in France finds two kinds of electricity exist, and Ben Franklin later labels them + and - . Like charges repel, unlike ones attract.
1745 --- The "Leyden Jar"
1752 --- Ben Franklin introduces the lightning rod, suggests lightning is great electric spark
1777 --- Charles Augustin Coulomb awarded prize for accurately measuring force between magnetic poles--at distance r, proportional to 1/r^2 Later modified his instrument to show that the force between electric charges has the same dependence on r 1786 --- Luigi Galvani, physician, find on dissecting frog legs that the touch of metal causes muscles to twitch.
1790-1800 --- Alessandro Volta shows that Galvani's "twitch" was caused by chemical reaction between metal and salty liquid. Invents electric cell and first battery of "Voltaic Pile"
1807 --- Humphry Davy
separates metallic potassium and sodium, by running an electric current through potassium chloride and sodium chloride salts, heated until they melted
ca. 1809 --- Humphry Davy
creates a brilliant "electric arc light" by running a large current from a 2000-cell "voltaic pile"
1813 --- Michael Faraday becomes assistant to Davy.
1820 --- Hans Kristian Oersted discovers that an electric current produces magnetic forces
1821 --- André-Marie d Ampére measures force between electric currents, claims it is the source of all magnetism.
Faraday uses this force to cause a wire dipping in mercury to rotate around a magnetic pole (and also the pole rotate around the wire)
1826 --- Joseph Henry invents the electromagnet
1827 --- Georg Simon Ohm discovers the law named for him
1831 --- Faraday discovers electromagnetic induction--electric current from motion of conductor in the region of magnetic force. Introduces magnetic field lines, comes to see them as "real".
1832 --- First magneto by
Hippolyte Pixii.
1836 --- Carl Friedrich Gauss measures the strength of the Earth's magnetism.
1837 ---
Charles Wheatstone and William Cooke invent a telegraph, used in Britain.
1842 --- Samuel Morse builds an electrical telegraph between Washington and Baltimore, introduces his signaling code
1846 ---
Faraday's lecture "Thoughts on Ray Vibrations"
1857-8 --- First trans-Atlantic telegraph cable
1861-73 ---
James Clerk Maxwell formulates the laws of electricity, includes the "displacement current", shows electromagnetic waves can exist and have the properties and velocity of light,
1876 ---
First electric telephones--by Alexander Graham Bell and Elisha Gray.
1877 ---
Thomas Alva Edison
invents the phonograph. Emile Berliner
invents the Carbon Granule Microphones, and in 1887, the flat phonograph record
1882 ---
Thomas Edison starts DC electric power station in New York City
1883 ---
Heinrich Hertz generates an electromagnetic wave by a spark and detects it some distance away
1884 ---
John Henry Poynting shows electromagnetic waves transmit energy and momentum.
1885 ---
Johannes Balmer in Switzerland finds formula for spectrum colors of hydrogen
1886 ---
Charles Hall (then a student at Oberlin College) and others initiate industrial production of aluminum by electrolysis. Nicholas Tesla and George Westinghouse experiment with AC electric power. In 1895 Westinghouse starts up AC power station at Niagara Falls.
1890 ---
London, England builds first electric railroad, a technology soon dominating city transportation above and below ground. Budapest follows in 1896.
1895 ---
X-rays discovered by
Roentgen
1896 ---
Discovery of electron by J.J. Thomson, Radioactivity discovered by Henri
Becquerel
1900 ---
Max Planck introduces the "quantum of energy" to explain electromagnetic radiation from hot solids
1903 ---
Gugliemo Marconi establishes first cross-Atlantic wireless link
from here on, just selected highlights:
1905 ---
Albert Einstein proposes that light is quantized in "photons", also the theory of relativity
1908 ---
Vacuum tube signal amplifier built by
Lee DeForest
1911 ---
Ernest Rutherford
shows that most of the mass of an atom is concentrated in a tiny positive nucleus, surrounded by negative electrons
1912 ---
The sinking passenger liner "Titanic" calls for help by radio
1914 ---
Niels Bohr suggests a quantum model of the hydrogen atom
1926 ---
The first "Enigma" coding machine
1927 --- Beginning of quantum mechanics
(Schroedinger, Heisenberg, Bohr)
1929 ---
Robert Van de Graaf invents charge generator for high voltages
~ 1936 --- developed (several independent efforts). Later developments sponsored by the Sperry Corporation and led by Victor Vacquier
1938-40 ---
John Atanasoff in Iowa, John William Mauchley in Philadelphia and others build early vacuum-tube computers
1942 ---
First nuclear reactor, based on instability of very heavy nuclei which are unable to withstand repulsion of positive electric charge inside their nuclei.
|
|