Timeline of electromagnetism and classical optics lists, within the history of electromagnetism, the associated theories, technology, and events.
Early developments
28th century BC – Ancient Egyptian texts describe electric fish. They refer to them as the "Thunderer of the Nile", and described them as the "protectors" of all other fish. 6th century BC – Greek philosopher Thales of Miletus observes that rubbing fur on various substances, such as amber, would cause an attraction between the two, which is now known to be caused by static 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. 424 BC Aristophanes' "lens" is a glass globe filled with water.(Seneca says that it can be used to read letters no matter how small or dim)The history of the telescope by Henry C. King, Harold Spencer Jones Publisher Courier Dover Publications, 2003 Pg 25 , 4th century BC Mo Di first mentions the camera obscura, a pin-hole camera. 3rd century BC Euclid is the first to write about reflection and refraction and notes that light travels in straight lines 3rd century BC – The Baghdad Battery is dated from this period. It resembles a galvanic cell and is believed by some to have been used for electroplating, although there is no common consensus on the purpose of these devices nor whether they were, indeed, even electrical in nature. 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". 130 AD – Claudius Ptolemy (in his work Optics) wrote about the properties of light including: reflection, refraction, and color and tabulated angles of refraction for several media 8th century AD – Electric fish are reported by Arabic naturalists and physicians.
Middle Ages 1021 – Ibn al-Haytham (Alhazen) writes the Book of Optics, studying vision. 1088 – Shen Kuo first recognizes magnetic declination. 1187 – Alexander Neckham is first in Europe to describe the magnetic compass and its use in navigation. 1269 – Pierre de Maricourt describes magnetic poles and remarks on the nonexistence of isolated magnetic poles 1282 – Al-Ashraf Umar II discusses the properties of magnets and dry compasses in relation to finding qibla. 1305 – Theodoric of Freiberg uses crystalline spheres and flasks filled with water to study the reflection and refraction in raindrops that leads to primary and secondary rainbows 14th century AD – Possibly the earliest and nearest approach to the discovery of the identity of lightning, and electricity from any other source, is to be attributed to the Arabs, who before the 15th century had the Arabic word for lightning (raad) applied to the electric ray.The Encyclopedia Americana; a library of universal knowledge (1918), New York City: Encyclopedia Americana Corp. 1550 – Gerolamo Cardano writes about electricity in De Subtilitate distinguishing, perhaps for the first time, between electrical and magnetic forces.
17th century 1600 – William Gilbert publishes De 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. His terrella (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. 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 in navigation due varying properties of the magnetic compass with respect to their location on the earth, such as magnetic declination and magnetic inclination. His experiments explained the dipping 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 by Shen Kuo in his Meng Xi Bi Tan and further investigated in 1581 by retired mariner and compass maker Robert Norman, as described in his pamphlet, The Newe Attractive. The gilbert, a unit of magnetomotive force or magnetic scalar potential, was named in his honor. 1604 – Johannes Kepler describes how the eye focuses light 1604 – Johannes Kepler specifies the laws of the rectilinear propagation of light 1608 – first telescopes appear in the Netherlands 1611 – Marko Dominis discusses the rainbow in De Radiis Visus et Lucis 1611 – Johannes Kepler discovers total internal reflection, a small-angle refraction law, and thin lens optics, c1620 – the first compound microscopes appear in Europe. 1621 – Willebrord van Roijen Snell states his Snell's law of refraction 1630 – Cabaeus finds that there are two types of electric charges 1637 – René Descartes quantitatively derives the angles at which primary and secondary rainbows are seen with respect to the angle of the Sun's elevation 1646 – Sir Thomas Browne first uses the word electricity is in his work Pseudodoxia Epidemica. 1657 – Pierre de Fermat introduces the principle of least time into optics 1660 – Otto von Guericke invents an early electrostatic generator. 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 the triboelectric 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. 1665 – Francesco Maria Grimaldi highlights the phenomenon of diffraction 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". 1675 – Isaac Newton delivers his theory of light 1676 – Ole Rømer proves that speed of light is finite, by observing Jupiter's moons 1678 – Christiaan Huygens states his principle of wavefront sources and demonstrates the refraction and diffraction of light rays.
18th century 1704 – Isaac Newton publishes Opticks, a corpuscular theory of light and colour 1705 – Francis Hauksbee improves von Guericke's electrostatic generator by using a glass globe and generates the first sparks by approaching his finger to the rubbed globe. 1728 – James Bradley discovers the aberration of starlight and uses it to determine that the speed of light is about 283,000 km/s 1729 – Stephen Gray and the Reverend Granville 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. This was also the first distinction between the roles of conductors and insulators (names applied by John Desaguliers, mathematician and Royal Society member, who stated that Gray "has made greater variety of electrical experiments than all the philosophers of this and the last age".) Georges-Louis LeSage built a static 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 the Philosophical 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, or gum-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 idea of two fluid was later replaced by the idea of too much or a lack of one fluid, termed positive and negative by William Watson and Benjamin Franklin. 1737 – C. F. du Fay and Francis Hauksbee the younger 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). 1740 – Jean le Rond d'Alembert, in Mémoire sur la réfraction des corps solides, explains the process of refraction. 1745 – Pieter van Musschenbroek of Leiden (Leyden) independently discovers the Leyden (Leiden) jar, a primitive capacitor or "condenser" (term coined by Volta in 1782, derived from the Italian condensatore), 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 (a dielectric) 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 causes electric current to flow and develops the concept of an electrical potential (voltage).