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Lightning Conductor
A lightning rod or lightning conductor (British English) is a metal rod mounted on a structure and intended to protect the structure from a lightning strike. If lightning hits the structure, it is most likely to strike the rod and be conducted to ground through a wire, rather than passing through the structure, where it could start a fire or even cause electrocution. Lightning rods are also called finials, air terminals, or strike termination devices. In a lightning protection system, a lightning rod is a single component of the system. The lightning rod requires a connection to the earth to perform its protective function. Lightning rods come in many different forms, including hollow, solid, pointed, rounded, flat strips, or even bristle brush-like. The main attribute common to all lightning rods is that they are all made of conductive materials, such as copper and aluminum. Copper and its alloys are the most common materials used in lightning protection. History The first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Vane
A wind vane, weather vane, or weathercock is an instrument used for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word ''vane'' comes from the Old English word , meaning "flag". Although partly functional, wind vanes are generally decorative, often featuring the traditional cockerel design with letters indicating the points of the compass. Other common motifs include ships, arrows, and horses. Not all wind vanes have pointers. In a sufficiently strong wind, the head of the arrow or cockerel (or equivalent) will indicate the direction from which the wind is blowing. Wind vanes are also found on small wind turbines to keep the wind turbine pointing into the wind. History The oldest known textual references to weather vanes date from 1800-1600 BCE Babylon, where a fable called ''The Fable of the Willow'' describes people looking at a weather vane "for the direction of the wind." In China, the ''Hu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or a gas). In electrochemical cells, electrodes are essential parts that can consist of a variety of materials (chemicals) depending on the type of cell. An electrode may be called either a cathode or anode according to the direction of the electric current, unrelated to the potential difference between electrodes. Michael Faraday coined the term "" in 1833; the word recalls the Greek ἤλεκτρον (, "amber") and ὁδός (, "path, way"). The electrophore, invented by Johan Wilcke in 1762, was an early version of an electrode used to study static electricity. Anode and cathode in electrochemical cells Electrodes are an essential part of any battery. The first electrochemical battery was devised by Alessandro Volta and was aptly named the Voltaic cell. This battery consisted of a stack of copper and zinc electrodes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Conductor
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. The flow of negatively charged electrons generates electric current, positively charged holes, and positive or negative ions in some cases. In order for current to flow within a closed electrical circuit, one charged particle does not need to travel from the component producing the current (the current source) to those consuming it (the loads). Instead, the charged particle simply needs to nudge its neighbor a finite amount, who will nudge ''its'' neighbor, and on and on until a particle is nudged into the consumer, thus powering it. Essentially what is occurring is a long chain of momentum transfer between mobile charge carriers; the Drude model of conduction describes this process more rigorously. This momentum transfer model makes metal an ideal choice f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground (electricity)
In electrical engineering, ground or earth may be a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth. Electrical circuits may be connected to ground for several reasons. Exposed conductive parts of electrical equipment are connected to ground to protect users from electrical shock hazards. If internal insulation fails, dangerous voltages may appear on the exposed conductive parts. Connecting exposed conductive parts to a "ground" wire which provides a low-impedance path for current to flow back to the incoming neutral (which is also connected to ground, close to the point of entry) will allow circuit breakers (or RCDs) to interrupt power supply in the event of a fault. In electric power distribution systems, a protective earth (PE) conductor is an essential part of the safety provided by the earthing system. Connection to ground also limits the build-up of static ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Current
An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge carriers, which may be one of several types of particles, depending on the Electrical conductor, conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or Electron hole, holes. In an Electrolyte#Electrochemistry, electrolyte the charge carriers are ions, while in Plasma (physics), plasma, an Ionization, ionized gas, they are ions and electrons. In the International System of Units (SI), electric current is expressed in Unit of measurement, units of ampere (sometimes called an "amp", symbol A), which is equivalent to one coulomb per second. The ampere is an SI base unit and electric current is a ISQ base quantity, base quantity in the International System of Qua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightning
Lightning is a natural phenomenon consisting of electrostatic discharges occurring through the atmosphere between two electrically charged regions. One or both regions are within the atmosphere, with the second region sometimes occurring on the land, ground. Following the lightning, the regions become partially or wholly electrically neutralized. Lightning involves a near-instantaneous release of energy on a scale averaging between 200 megajoules and 7 gigajoules. The air around the lightning flash rapidly heats to temperatures of about . There is an emission of electromagnetic radiation across a wide range of wavelengths, some visible as a bright flash. Lightning also causes thunder, a sound from the shock wave which develops as heated gases in the vicinity of the discharge experience a sudden increase in pressure. The most common occurrence of a lightning event is known as a thunderstorm, though they can also commonly occur in other types of energetic weather systems, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlas V 551 At Launch Pad 41
An atlas is a collection of maps; it is typically a bundle of world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditionally been bound into book form, but today, many atlases are in multimedia formats. In addition to presenting geography, geographical features and border, political boundaries, many atlases often feature geopolitical, social, religious, and economic statistics. They also have information about the map and places in it. Etymology The use of the word "atlas" in a geographical context dates from 1595 when the German-Flemish geographer Gerardus Mercator published ("Atlas or cosmographical meditations upon the creation of the universe and the universe as created"). This title provides Mercator's definition of the word as a description of the creation and form of the whole universe, not simply as a collection of maps. The volume that was publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statue Of Liberty
The Statue of Liberty (''Liberty Enlightening the World''; ) is a colossal neoclassical sculpture on Liberty Island in New York Harbor, within New York City. The copper-clad statue, a gift to the United States from the people of French Third Republic, France, was designed by French sculptor Frédéric Auguste Bartholdi and its metal framework was built by Gustave Eiffel. The statue was dedicated on October 28, 1886. The statue is a figure of a classically draped woman, likely inspired by the Roman Liberty (personification), goddess of liberty, Libertas. In a contrapposto pose, she holds a torch above her head with her right hand, and in her left hand carries a ''tabula ansata'' inscribed JULY IV MDCCLXXVI (July 4, 1776, in Roman numerals), the date of the U.S. Declaration of Independence. With her left foot she steps on a broken chain and shackle, commemorating the End of slavery in the United States, national abolition of slavery following the American Civil War. After its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statue Of Freedom
The ''Statue of Freedom'', also known as ''Armed Freedom'' or simply ''Freedom'', is a bronze statue designed by Thomas Crawford (sculptor), Thomas Crawford that, since 1863, has crowned the United States Capitol dome. Originally named ''Freedom Triumphant in War and Peace'', a U.S. government publication now states that the statue "is officially known as the ''Statue of Freedom''." The statue depicts a female figure bearing a military helmet and holding a sheathed sword in her right hand and a laurel wreath and shield in her left. Description The ''Statue of Freedom'' is a colossal bronze figure standing tall and weighing approximately 15,000 pounds (6,800 kg). Her crest peaks at 288 feet (88 m) above the east front plaza of the U.S. Capitol. She is an allegory, allegorical figure whose right hand holds the hilt of a sheathed sword, while a laurel wreath of victory and the Shield of the United States are clasped in her left hand. Her Chiton (costume), chiton is secured by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperial Russian Navy
The Imperial Russian Navy () operated as the navy of the Russian Tsardom and later the Russian Empire from 1696 to 1917. Formally established in 1696, it lasted until being dissolved in the wake of the February Revolution and the declaration of the Russian Republic in 1917. It developed from a smaller force that had existed prior to Tsar Peter the Great's founding of the modern Russian navy during the Azov campaigns (1695–1696), Second Azov campaign in 1696, and expanded in the second half of the 18th century before reaching its peak strength by the early part of the 19th century, behind only the British and French fleets in terms of size. The Imperial Navy drew its officers from the aristocracy of the Empire, who belonged to the state Russian Orthodox Church. Young aristocrats began to be trained for leadership at a national naval boarding school, the Naval Cadet Corps (Russia), Naval Cadet Corps. From 1818 on, only officers of the Imperial Russian Navy were appointed to the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
