28th century BC –Ancient Egyptian texts describeelectric fish. They refer to them as the "Thunderer of theNile", and described them as the "protectors" of all other fish.[1]
6th century BC –Greek philosopherThales of Miletus observes that rubbing fur on various substances, such asamber, would cause an attraction between the two, which is now known to be caused bystatic electricity. He noted that rubbing the amber buttons could attract light objects such as hair and that if the amber was rubbed sufficiently a spark would jump.[2][3]
424 BCAristophanes' "lens" is a glass globe filled with water.(Seneca says that it can be used to read lettersno matter how small or dim)[4]
3rd century BCEuclid is the first to write about reflection and refraction and notes that light travels in straight lines[4]
3rd century BC – TheBaghdad Battery is dated from this period. It resembles agalvanic cell and is believed by some to have been used forelectroplating, although there is no common consensus on the purpose of these devices nor whether they were, indeed, even electrical in nature.[5]
1st century AD – Pliny in his Natural History records the story of a shepherd Magnes who discovered the magnetic properties of some iron stones, "it is said, made this discovery, when, upon taking his herds to pasture, he found that the nails of his shoes and the iron ferrel of his staff adhered to the ground".[6]
1282 –Al-Ashraf Umar II discusses the properties of magnets and dry compasses in relation to findingqibla.[7]
1305 –Theodoric of Freiberg uses crystalline spheres and flasks filled with water to study thereflection and refraction in raindrops that leads to primary and secondaryrainbows
14th century AD – Possibly the earliest and nearest approach to the discovery of the identity oflightning, andelectricity from any other source, is to be attributed to theArabs, who before the 15th century had theArabic word for lightning (raad) applied to theelectric ray.[8]
1550 –Gerolamo Cardano writes about electricity inDe Subtilitate distinguishing, perhaps for the first time, between electrical and magnetic forces.[citation needed]
1600 –William Gilbert publishesDe Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure ("On the Magnet and Magnetic bodies, and on that Great Magnet the Earth"), Europe's then current standard on electricity and magnetism. He experimented with and noted the different character of electrical and magnetic forces. In addition to known ancient Greeks' observations of the electrical properties of rubbed amber, he experimented with a needle balanced on a pivot, and found that the needle was non-directionally affected by many materials such as alum, arsenic, hard resin,jet, glass, gum-mastic, mica, rock-salt, sealing wax, slags, sulfur, and precious stones such as amethyst,beryl, diamond, opal, and sapphire. He noted that electrical charge could be stored by covering the body with a non-conducting substance such as silk. He described the method of artificially magnetizing iron. Histerrella (little earth), a sphere cut from a lodestone on a metal lathe, modeled the earth as a lodestone (magnetic iron ore) and demonstrated that every lodestone has fixed poles, and how to find them.[9] He considered that gravity was a magnetic force and noted that this mutual force increased with the size or amount of lodestone and attracted iron objects. He experimented with such physical models in an attempt to explain problems innavigation due varying properties of themagnetic compass with respect to their location on the earth, such asmagnetic declination and magnetic inclination. His experiments explained thedipping of the needle by the magnetic attraction of the earth, and were used to predict where the vertical dip would be found. Such magnetic inclination was described as early as the 11th century byShen Kuo in hisMeng Xi Bi Tan and further investigated in 1581 by retired mariner andcompass makerRobert Norman, as described in his pamphlet,The Newe Attractive. The gilbert, a unit ofmagnetomotive force ormagnetic scalar potential, was named in his honor.
1637 –René Descartes quantitatively derives the angles at which primary and secondary rainbows are seen with respect to the angle of theSun's elevation
1663 –Otto von Guericke (brewer and engineer who applied the barometer to weather prediction and invented the air pump, with which he demonstrated the properties of atmospheric pressure associated with a vacuum) constructs a primitive electrostatic generating (or friction) machine via thetriboelectric effect, utilizing a continuously rotating sulfur globe that could be rubbed by hand or a piece of cloth.Isaac Newton suggested the use of a glass globe instead of a sulfur one.
1673 – Ignace Pardies provides a wave explanation for refraction of light
1675 –Robert Boyle discovers that electric attraction and repulsion can act across a vacuum and do not depend upon the air as a medium. Adds resin to the known list of "electrics".
1704 –Isaac Newton publishesOpticks, a corpuscular theory of light and colour
1705 –Francis Hauksbee improves von Guericke'selectrostatic generator by using a glass globe and generates the first sparks by approaching his finger to the rubbed globe.
1729 –Stephen Gray and the ReverendGranville Wheler experiment to discover that electrical "virtue", produced by rubbing a glass tube, could be transmitted over an extended distance (nearly 900 ft (about 270 m)) through thin iron wire using silk threads as insulators, to deflect leaves of brass. This has been described as the beginning of electrical communication.[11][page needed] This was also the first distinction between the roles of conductors and insulators (names applied byJohn Desaguliers, mathematician andRoyal Society member, who stated that Gray "has made greater variety of electrical experiments than all the philosophers of this and the last age".)[11][page needed] Georges-Louis LeSage built astatic electricity telegraph in 1774, based upon the same principles discovered by Gray.
1732 –C. F. du Fay Shows that all objects, except metals, animals, and liquids, can be electrified by rubbing them and that metals, animals and liquids could be electrified by means of an electrostatic generators
1734 –Charles François de Cisternay DuFay (inspired by Gray's work to perform electrical experiments) dispels the effluvia theory by his paper in Volume 38 of thePhilosophical Transactions of the Royal Society, describing his discovery of the distinction between two kinds of electricity: "resinous", produced by rubbing bodies such as amber, copal, orgum-lac with silk or paper, and "vitreous", by rubbing bodies as glass, rock crystal, or precious stones with hair or wool. He also posited the principle of mutual attraction for unlike forms and the repelling of like forms and that "from this principle one may with ease deduce the explanation of a great number of other phenomena". The terms resinous and vitreous were later replaced with the terms "positive" and "negative" byWilliam Watson and Benjamin Franklin.
1737 –C. F. du Fay andFrancis Hauksbee the younger[citation needed] independently discover two kinds of frictional electricity: one generated from rubbing glass, the other from rubbing resin (later identified as positive and negative electrical charges).
1745 –Pieter van Musschenbroek of Leiden (Leyden) independently discovers theLeyden (Leiden) jar, a primitivecapacitor or "condenser" (term coined by Volta in 1782, derived from the Italiancondensatore), with which the transient electrical energy generated by current friction machines could now be stored. He and his student Andreas Cunaeus used a glass jar filled with water into which a brass rod had been placed. He charged the jar by touching a wire leading from the electrical machine with one hand while holding the outside of the jar with the other. The energy could be discharged by completing an external circuit between the brass rod and another conductor, originally his hand, placed in contact with the outside of the jar. He also found that if the jar were placed on a piece of metal on a table, a shock would be received by touching this piece of metal with one hand and touching the wire connected to the electrical machine with the other.
1745 –Ewald Georg von Kleist of independently invents the capacitor: a glass jar coated inside and out with metal. The inner coating was connected to a rod that passed through the lid and ended in a metal sphere. By having this thin layer of glass insulation (adielectric) between two large, closely spaced plates, von Kleist found the energy density could be increased dramatically compared with the situation with no insulator.Daniel Gralath improved the design and was also the first to combine several jars to form a battery strong enough to kill birds and small animals upon discharge.
1746 –Leonhard Euler develops the wave theory of light refraction and dispersion
1747 –William Watson, while experimenting with a Leyden jar, observes that a discharge of static electricity causeselectric current to flow and develops the concept of an electrical potential (voltage).
1752 –Benjamin Franklin establishes the link between lightning and electricity by the flying a kite into a thunderstorm and transferring some of the charge into a Leyden jar and showed that its properties were the same as charge produced by an electrical machine. He is credited with utilizing the concepts of positive and negative charge in the explanation of then known electrical phenomenon. He theorized that there was an electrical fluid (which he proposed could be theluminiferous ether, which was used by others before and after him, to explain thewave theory of light) that was part of all material and all intervening space. The charge of any object would be neutral if the concentration of this fluid were the same both inside and outside of the body, positive if the object contained an excess of this fluid, and negative if there were a deficit. In 1749 he had documented the similar properties of lightning and electricity, such as that both anelectric spark and a lightning flash produced light and sound, could kill animals, cause fires, melt metal, destroy or reverse the polarity of magnetism, and flowed through conductors and could be concentrated at sharp points. He was later able to apply the property of concentrating at sharp points by his invention of the lightning rod, for which he intentionally did not profit. He also investigated the Leyden jar, proving that the charge was stored on the glass and not in the water, as others had assumed.
1753 – C. M. (of Scotland, possibly Charles Morrison, of Greenock or Charles Marshall, of Aberdeen) proposes in 17 February edition of Scots Magazine, an electrostatic telegraph system with 26 insulated wires, each corresponding to a letter of the alphabet and each connected to electrostatic machines. The receiving charged end was to electrostatically attract a disc of paper marked with the corresponding letter.
1767 –Joseph Priestley proposes an electrical inverse-square law
1774 –Georges-Louis LeSage builds an electrostatic telegraph system with 26 insulated wires conducting Leyden-jar charges to pith-ball electroscopes, each corresponding to a letter of the alphabet. Its range was only between rooms of his home.
1784 –Henry Cavendish defines theinductive capacity ofdielectrics (insulators) and measures the specific inductive capacity of various substances by comparison with an air condenser.
1786 –Luigi Galvani discovers "animal electricity" and postulates that animal bodies are storehouses of electricity. His invention of the voltaic cell leads to the invention the electric battery.
1791 –Luigi Galvani discovers galvanic electricity andbioelectricity through experiments following an observation that touching exposed muscles in frogs' legs with a scalpel which had been close to a static electrical machine caused them to jump. He called this "animal electricity". Years of experimentation in the 1780s eventually led him to the construction of an arc of two different metals (copper and zinc for example) by connecting the two metal pieces and then connecting their open ends across the nerve of a frog leg, producing the same muscular contractions (by completing a circuit) as originally accidentally observed. The use of different metals to produce an electrical spark is the basis that led Alessandro Volta in 1799 to his invention of his voltaic pile, which eventually became thegalvanic battery.[12]
1799 –Alessandro Volta, following Galvani's discovery of galvanic electricity, creates avoltaic cell producing an electric current by the chemical action of several pairs of alternating copper (or silver) and zinc discs "piled" and separated by cloth or cardboard which had been soaked brine (salt water) or acid to increase conductivity. In1800 he demonstrates the production of light from a glowing wire conducting electricity. This was followed in 1801 by his construction of the firstelectric battery, by utilizing multiple voltaic cells. Prior to his major discoveries, in a letter of praise to the Royal Society 1793, Volta reported Luigi Galvani's experiments of the 1780s as the "most beautiful and important discoveries", regarding them as the foundation of future discoveries. Volta's inventions led to revolutionary changes with this method of the production of inexpensive, controlled electric current vs. existing frictional machines and Leyden jars. The electric battery became standard equipment in every experimental laboratory and heralded an age of practical applications of electricity.[11][page needed] The unitvolt is named for his contributions.
1802 –Gian Domenico Romagnosi, Italian legal scholar, discovers that electricity and magnetism are related by noting that a nearby voltaic pile deflects a magnetic needle. He published his account in an Italian newspaper, but this was overlooked by the scientific community.[14]
1806 –Alessandro Volta employs a voltaic pile to decompose potash and soda, showing that they are the oxides of the previously unknown metals potassium and sodium. These experiments were the beginning ofelectrochemistry.
1820 –Hans Christian Ørsted, Danish physicist and chemist, develops an experiment in which he notices a compass needle is deflected frommagnetic north when an electric current from the battery he was using was switched on and off, convincing him that magnetic fields radiate from all sides of a live wire just as light and heat do, confirming a direct relationship between electricity and magnetism. He also observes that the movement of the compass-needle to one side or the other depends upon the direction of the current.[16] Following intensive investigations, he published his findings, proving that a changing electric current produces a magnetic field as it flows through a wire. Theoersted unit of magnetic induction is named for his contributions.
1820 –André-Marie Ampère, professor of mathematics at the École Polytechnique, demonstrates that parallel current-carrying wires experience magnetic force in a meeting of theFrench Academy of Sciences, exactly one week after Ørsted's announcement of his discovery that a magnetic needle is acted on by a voltaic current.[17] He shows that a coil of wire carrying a current behaves like an ordinary magnet and suggests that electromagnetism might be used in telegraphy. He mathematically developsAmpère's law describing the magnetic force between two electric currents. His mathematical theory explains known electromagnetic phenomena and predicts new ones. His laws of electrodynamics include the facts that parallel conductors currying current in the same direction attract and those carrying currents in the opposite directions repel one another. One of the first to develop electrical measuring techniques, he built an instrument utilizing a free-moving needle to measure the flow of electricity, contributing to the development of thegalvanometer. In1821, he proposed a telegraphy system utilizing one wire per "galvanometer" to indicate each letter, and reported experimenting successfully with such a system. However, in1824,Peter Barlow reported its maximum distance was only 200 feet, and so was impractical.[citation needed] In1826 he publishes theMemoir on the Mathematical Theory of Electrodynamic Phenomena, Uniquely Deduced from Experience containing a mathematical derivation of the electrodynamic force law. Following Faraday's discovery of electromagnetic induction in 1831, Ampère agreed that Faraday deserved full credit for the discovery.
1820 –Johann Salomo Christoph Schweigger, German chemist, physicist, and professor, builds the first sensitive galvanometer, wrapping a coil of wire around a graduated compass, an acceptable instrument for actual measurement as well as detection of small amounts of electric current, naming it after Luigi Galvani.
1821 –André-Marie Ampère announces his theory of electrodynamics, predicting the force that one current exerts upon another.
1821 –Augustin-Jean Fresnel derives a mathematical demonstration that polarization can be explained only if light isentirely transverse, with no longitudinal vibration whatsoever.
1825 –William Sturgeon, founder of the first English Electric Journal,Annals of Electricity, found that an iron core inside a helical coil of wire connected to a battery greatly increased the resulting magnetic field, thus making possible the more powerfulelectromagnets utilizing aferromagnetic core. Sturgeon also bent the iron core into a U-shape to bring the poles closer together, thus concentrating the magnetic field lines. These discoveries followed Ampère's discovery that electricity passing through a coiled wire produced a magnetic force and that ofDominique François Jean Arago finding that an iron bar is magnetized by putting it inside the coil of current-carrying wire, but Arago had not observed the increased strength of the resulting field while the bar was being magnetized.
1826 –Georg Simon Ohm states hisOhm's law ofelectrical resistance in the journals of Schweigger and Poggendorff, and also published in his landmark pamphletDie galvanische Kette mathematisch bearbeitet in1827. The unitohm (Ω) of electrical resistance has been named in his honor.[18]
1829 & 1830 –Francesco Zantedeschi publishes papers on the production of electric currents in closed circuits by the approach and withdrawal of a magnet, thereby anticipating Michael Faraday's classical experiments of 1831.
1831 –Michael Faraday began experiments leading to his discovery of the law ofelectromagnetic induction, though the discovery may have been anticipated by the work of Francesco Zantedeschi. His breakthrough came when he wrapped two insulated coils of wire around a massive iron ring, bolted to a chair, and found that upon passing a current through one coil, a momentary electric current was induced in the other coil. He then found that if he moved a magnet through a loop of wire, or vice versa, an electric current also flowed in the wire. He then used this principle to construct theelectric dynamo, the first electric power generator. He proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete that work. Faraday's concept of lines of flux emanating from charged bodies and magnets provided a way to visualize electric and magnetic fields. That mental model was crucial to the successful development of electromechanical devices which were to dominate the 19th century. His demonstrations that a changing magnetic field produces an electric field, mathematically modeled byFaraday's law of induction, would subsequently become one ofMaxwell's equations. These consequently evolved into the generalization offield theory.
1832 –Baron Pavel L'vovitch Schilling (Paul Schilling) creates the first electromagnetic telegraph, consisting of a single-needle system in which a code was used to indicate the characters. Only months later, Göttingen professorsCarl Friedrich Gauss andWilhelm Weber constructed a telegraph that was working two years before Schilling could put his into practice. Schilling demonstrated the long-distance transmission of signals between two different rooms of his apartment and was the first to put into practice a binary system of signal transmission.
1833 –Heinrich Lenz statesLenz's law: if an increasing (or decreasing) magnetic flux induces anelectromotive force (EMF), the resulting current will oppose a further increase (or decrease) in magnetic flux, i.e., that an induced current in a closed conducting loop will appear in such a direction that it opposes the change that produced it. Lenz's law is one consequence of the principle ofconservation of energy. If a magnet moves towards a closed loop, then the induced current in the loop creates a field that exerts a force opposing the motion of the magnet. Lenz's law can be derived fromFaraday's law of induction by noting the negative sign on the right side of the equation. He also independently discoveredJoule's law in1842; to honor his efforts, Russian physicists refer to it as the "Joule–Lenz law".
1835 –Joseph Henry invents theelectric relay, which is an electrical switch by which the change of a weak current through the windings of an electromagnet will attract an armature to open or close the switch. Because this can control (by opening or closing) another, much higher-power, circuit, it is in a broad sense a form of electrical amplifier. This made a practical electric telegraph possible. He was the first to coil insulated wire tightly around an iron core in order to make an extremely powerful electromagnet, improving on William Sturgeon's design, which used loosely coiled, uninsulated wire. He also discovered the property ofself inductance independently of Michael Faraday.
Chart of the InternationalMorse code letters and numerals.
1837 –Samuel Morse develops an alternative electrical telegraph design capable of transmitting long distances over poor quality wire. He and his assistantAlfred Vail develop theMorse code signaling alphabet. In1838 Morse successfully tested the device at the Speedwell Ironworks nearMorristown, New Jersey, and publicly demonstrated it to a scientific committee at theFranklin Institute inPhiladelphia, Pennsylvania. The first electric telegram using this device was sent by Morse on 24 May,1844 from Baltimore to Washington, D.C., bearing the message "What hath God wrought?"
1840 –James Prescott Joule formulatesJoule's Law (sometimes called the Joule-Lenz law) quantifying the amount of heat produced in a circuit as proportional to the product of the time duration, the resistance, and the square of the current passing through it.
1854 –Gustav Robert Kirchhoff, physicist and one of the founders ofspectroscopy, publishesKirchhoff's Laws on the conservation of electric charge and energy, which are used to determine currents in each branch of a circuit.
1861 – thefirst transcontinental telegraph system spans North America by connecting an existing network in the eastern United States to a small network in California by a link between Omaha and Carson City via Salt Lake City. The slower Pony Express system ceased operation a month later.
1865 –James Clerk Maxwell publishes his landmark paperA Dynamical Theory of the Electromagnetic Field, in whichMaxwell's equations demonstrated that electric andmagnetic forces are two complementary aspects ofelectromagnetism. He shows that the associated complementary electric and magnetic fields of electromagnetism travel through space, in the form of waves, at a constant velocity of3.0×108 m/s. He also proposes that light is a form of electromagnetic radiation and that waves of oscillating electric and magnetic fields travel through empty space at a speed that could be predicted from simple electrical experiments. Using available data, he obtains a velocity of310740000 m/s and states "This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and otherradiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws."
1866 – the first successfultransatlantic telegraph system was completed. Earlier submarine cable transatlantic cables installed in 1857 and 1858 failed after operating for a few days or weeks.
1875 –John Kerr discovers the electrically induced birefringence of some liquids
1878 –Thomas Edison, following work on a "multiplex telegraph" system and the phonograph, invents an improved incandescent light bulb. This was not the first electric light bulb but the first commercially practical incandescent light. In1879 he produces a high-resistance lamp in a very high vacuum; the lamp lasts hundreds of hours. While the earlier inventors had produced electric lighting in lab conditions, Edison concentrated on commercial application and was able to sell the concept to homes and businesses by mass-producing relatively long-lasting light bulbs and creating a complete system for the generation and distribution of electricity.
1882 – Edison switches on the world's first electrical power distribution system, providing 110 voltsdirect current (DC) to 59 customers.
1884 –Oliver Heaviside reformulates Maxwell's original mathematical treatment of electromagnetic theory from twenty equations in twenty unknowns into four simple equations in four unknowns (the modern vector form ofMaxwell's equations).
1887 –Heinrich Hertz invents a device for the production and reception of electromagnetic (EM) radio waves. His receiver consists of a coil with a spark gap.
1888 –Heinrich Hertz demonstrates the existence of electromagnetic waves by building an apparatus that produced and detected UHF radio waves (or microwaves in the UHF region). He also found that radio waves could be transmitted through different types of materials and were reflected by others, the key toradar. His experiments explainreflection,refraction,polarization,interference, andvelocity of electromagnetic waves.
1900 –Max Planck resolves theultraviolet catastrophe by suggesting thatblack-body radiation consists of discrete packets, orquanta, of energy. The amount of energy in each packet is proportional to the frequency of the electromagnetic waves. The constant of proportionality is now called thePlanck constant in his honor.
1911 –Superconductivity is discovered byHeike Kamerlingh Onnes, who was studying the resistivity of solid mercury at cryogenic temperatures using the recently discovered liquid helium as a refrigerant. At the temperature of 4.2 K, he observed that the resistivity abruptly disappeared. For this discovery, he was awarded the Nobel Prize in Physics in 1913.
^Pliny the Elder. "Dedication".The Natural History. Perseus Collection: Greek and Roman Materials. Department of the Classics, Tufts University. Retrieved20 October 2015.
^Schmidl, Petra G. (1996–1997). "Two Early Arabic Sources On The Magnetic Compass".Journal of Arabic and Islamic Studies.1:81–132.
^TheEncyclopedia Americana; a library of universal knowledge (1918), New York City: Encyclopedia Americana Corp.
^Williams, Henry Smith. "Part IV. William Gilbert and the Study of Magnetism".A history of science. Vol. 2. Worldwide School. Archived fromthe original on 17 January 2008. Retrieved20 October 2015.
^Williams, Henry Smith. "VII. The Modern Development of Electricity and Magnetism".A history of science. Vol. 3. Worldwide School. Retrieved20 October 2015.
^Martins, Roberto de Andrade. "Romagnosi and Volta's pile: early difficulties in the interpretation of Voltaic electricity". In Bevilacqua, Fabio; Fregonese, Lucio (eds.).Nuova Voltiana: Studies on Volta and his Times. Vol. 3. Pavia: Ulrico Hoepli. pp. 81–102.
