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History Of Electromagnetism
The history of electromagnetic theory begins with ancient measures to understand atmospheric electricity, in particular lightning. People then had little understanding of electricity, and were unable to explain the phenomena. Scientific understanding into the nature of electricity grew throughout the eighteenth and nineteenth centuries through the work of researchers such as Coulomb, Ampère, Faraday and Maxwell. In the 19th century it had become clear that electricity and magnetism were related, and their theories were unified: wherever charges are in motion electric current results, and magnetism is due to electric current.Lyons, T. A. (1901). ''A treatise on electromagnetic phenomena, and on the compass and its deviations aboard ship. Mathematical, theoretical, and practical''. New York: J. Wiley & Sons. The source for electric field is electric charge, whereas that for magnetic field is electric current (charges in motion). Ancient and classical history The knowledge of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Electricity
Atmospheric electricity is the study of electrical charges in the Earth's atmosphere (or that of another planet). The movement of charge between the Earth's surface, the atmosphere, and the ionosphere is known as the global atmospheric electrical circuit. Atmospheric electricity is an interdisciplinary topic with a long history, involving concepts from electrostatics, atmospheric physics, meteorology and Earth science. Thunderstorms act as a giant battery in the atmosphere, charging up the electrosphere to about 400,000 volts with respect to the surface. This sets up an electric field throughout the atmosphere, which decreases with increase in altitude. Atmospheric ions created by cosmic rays and natural radioactivity move in the electric field, so a very small current flows through the atmosphere, even away from thunderstorms. Near the surface of the Earth, the magnitude of the field is on average around 100 V/m. Atmospheric electricity involves both thunderstorms, which c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A History Of The Theories Of Aether And Electricity
''A History of the Theories of Aether and Electricity'' is any of three books written by British mathematician Sir Edmund Taylor Whittaker FRS FRSE on the history of electromagnetic theory, covering the development of classical electromagnetism, optics, and aether theories. The book's first edition, subtitled ''from the Age of Descartes to the Close of the Nineteenth Century'', was published in 1910 by Longmans, Green. The book covers the history of aether theories and the development of electromagnetic theory up to the 20th century. A second, extended and revised, edition consisting of two volumes was released in the early 1950s by Thomas Nelson, expanding the book's scope to include the first quarter of the 20th century. The first volume, subtitled ''The Classical Theories'', was published in 1951 and served as a revised and updated edition to the first book. The second volume, subtitled ''The Modern Theories (1900–1926)'', was published two years later in 1953, extende ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Catfish
Electric catfish or Malapteruridae is a family of catfishes (order Siluriformes). This family includes two genera, '' Malapterurus'' and '' Paradoxoglanis'', with 21 species. Several species of this family have the ability to generate electricity, delivering a shock of up to 350 volts from its electric organ. Electric catfish are found in tropical Africa and the Nile River. Electric catfish are usually nocturnal and carnivorous. Some species feed primarily on other fish, incapacitating their prey with electric discharges, but others are generalist bottom foragers, feeding on things like invertebrates, fish eggs, and detritus. The largest can grow to about 1.2 meters (3 ft) long, but most species are far smaller. Description The Malapteruridae are the only group of catfish with well-developed electrogenic organs; however, electroreceptive systems are widespread in catfishes. The electrogenic organ is derived from anterior body musculature and lines the body cavity. Electric cat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Fish
An electric fish is any fish that can generate electric fields. Most electric fish are also electroreceptive, meaning that they can sense electric fields. The only exception is the stargazer family. Electric fish, although a small minority, include both oceanic and freshwater species, and both cartilaginous and bony fishes. Electric fish produce their electrical fields from an electric organ. This is made up of electrocytes, modified muscle or nerve cells, specialized for producing strong electric fields, used to locate prey, for defence against predators, and for signalling, such as in courtship. Electric organ discharges are two types, pulse and wave, and vary both by species and by function. Electric fish have evolved many specialised behaviours. The predatory African sharptooth catfish eavesdrops on its weakly electric mormyrid prey to locate it when hunting, driving the prey fish to develop electric signals that are harder to detect. Bluntnose knifefishes produce an el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetism
In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of atoms and molecules. Electromagnetism can be thought of as a combination of electricity and magnetism, two distinct but closely intertwined phenomena. In essence, electric forces occur between any two charged particles, causing an attraction between particles with opposite charges and repulsion between particles with the same charge, while magnetism is an interaction that occurs exclusively between ''moving'' charged particles. These two effects combine to create electromagnetic fields in the vicinity of charge particles, which can exert influence on other particles via the Lorentz force. At high energy, the weak force and electromagnetic force are unified as a single electroweak force. The electromagnetic force is responsible for m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malapterurus Electricus 1
''Malapterurus'' is a genus of catfishes (order Siluriformes) of the electric catfish family (Malapteruridae). It includes 18 species. Distribution The genus ''Malapterurus'' is found throughout western and central tropical Africa and the Nile River. They occur in all major freshwater systems including the Buzi, Niger, Ogooué, Omo, Sanaga, Sabi-Lundi, Senegal, Shari, Congo, and Zambezi River basins, as well as Lakes Albert, Chad, Kainji, Tanganyika, and Turkana. Description ''Malapterurus'' have an elongate and cylindrical body that gives them the general appearance of a sausage. The eyes are small, the lips are rather thick, and the snout is rounded with widely separated nostrils. The gill openings are narrow and restricted to the sides. ''Malapterurus'' species have three pairs of barbels, and lack a dorsal fin. The pectoral, pelvic, and caudal fins are rounded. The swimbladder has two elongate posterior chambers. Species in ''Malapterurus'' are generally grayish-br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance of the chemical elements#Earth, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer core, outer and inner core. It is the fourth most common abundance of elements in Earth's crust, element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or Metallurgical furnace, furnaces capable of reaching or higher, about higher than that required to smelting, smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC, 2nd millennium BC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Book Of The Devil Valley Master
A book is a medium for recording information in the form of writing or images, typically composed of many pages (made of papyrus, parchment, vellum, or paper) bound together and protected by a cover. The technical term for this physical arrangement is '' codex'' (plural, ''codices''). In the history of hand-held physical supports for extended written compositions or records, the codex replaces its predecessor, the scroll. A single sheet in a codex is a leaf and each side of a leaf is a page. As an intellectual object, a book is prototypically a composition of such great length that it takes a considerable investment of time to compose and still considered as an investment of time to read. In a restricted sense, a book is a self-sufficient section or part of a longer composition, a usage reflecting that, in antiquity, long works had to be written on several scrolls and each scroll had to be identified by the book it contained. Each part of Aristotle's ''Physics'' is called a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomancy
Geomancy ( Greek: γεωμαντεία, "earth divination") is a method of divination that interprets markings on the ground or the patterns formed by tossed handfuls of soil, rocks, or sand. The most prevalent form of divinatory geomancy involves interpreting a series of 16 figures formed by a randomized process that involves recursion, followed by analyzing them, often augmented with astrological interpretations. Geomancy was practiced by people from all social classes. It was one of the most popular forms of divination throughout Africa and Europe, particularly during the Middle Ages and the Renaissance. In Renaissance magic, geomancy was classified as one of the seven "forbidden arts", along with necromancy, hydromancy, aeromancy, pyromancy, chiromancy ( palmistry), and spatulamancy ( scapulimancy). History The word "geomancy", from Late Greek ''geōmanteía'', translates literally to "foresight by earth"; it is a calque translation of the Arabic term ''‛ilm al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central America
Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. Central America consists of eight countries: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, and Panama. Within Central America is the Mesoamerican biodiversity hotspot, which extends from northern Guatemala to central Panama. Due to the presence of several active geologic faults and the Central America Volcanic Arc, there is a high amount of seismic activity in the region, such as volcanic eruptions and earthquakes which has resulted in death, injury, and property damage. In the pre-Columbian era, Central America was inhabited by the indigenous peoples of Mesoamerica to the north and west and the Isthmo-Colombian peoples to the south and east. Following the Spanish expedition of Christopher Columbus' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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