113-525: The Electricity Association ( EA ) was an association of major electricity companies in the United Kingdom . It closed on 30 September 2003, and its services were replaced by three other industry bodies: This article related to the history of the United Kingdom or its predecessor states is a stub . You can help Misplaced Pages by expanding it . Electricity Electricity is
226-455: A conductor 's surface, since otherwise there would be a force along the surface of the conductor that would move the charge carriers to even the potential across the surface. The electric field was formally defined as the force exerted per unit charge, but the concept of potential allows for a more useful and equivalent definition: the electric field is the local gradient of the electric potential. Usually expressed in volts per metre,
339-461: A force on each other, an effect that was known, though not understood, in antiquity. A lightweight ball suspended by a fine thread can be charged by touching it with a glass rod that has itself been charged by rubbing with a cloth. If a similar ball is charged by the same glass rod, it is found to repel the first: the charge acts to force the two balls apart. Two balls that are charged with a rubbed amber rod also repel each other. However, if one ball
452-409: A steady state current, but instead blocks it. The inductor is a conductor, usually a coil of wire, that stores energy in a magnetic field in response to the current through it. When the current changes, the magnetic field does too, inducing a voltage between the ends of the conductor. The induced voltage is proportional to the time rate of change of the current. The constant of proportionality
565-456: A central role in many modern technologies, serving in electric power where electric current is used to energise equipment, and in electronics dealing with electrical circuits involving active components such as vacuum tubes , transistors , diodes and integrated circuits , and associated passive interconnection technologies. The study of electrical phenomena dates back to antiquity, with theoretical understanding progressing slowly until
678-432: A charge of Q coulombs every t seconds passing through an electric potential ( voltage ) difference of V is where Electric power is generally supplied to businesses and homes by the electric power industry . Electricity is usually sold by the kilowatt hour (3.6 MJ) which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using electricity meters , which keep
791-516: A common reference point to which potentials may be expressed and compared is useful. While this could be at infinity, a much more useful reference is the Earth itself, which is assumed to be at the same potential everywhere. This reference point naturally takes the name earth or ground . Earth is assumed to be an infinite source of equal amounts of positive and negative charge and is therefore electrically uncharged—and unchargeable. Electric potential
904-472: A current of one amp. The capacitor is a development of the Leyden jar and is a device that can store charge, and thereby storing electrical energy in the resulting field. It consists of two conducting plates separated by a thin insulating dielectric layer; in practice, thin metal foils are coiled together, increasing the surface area per unit volume and therefore the capacitance . The unit of capacitance
1017-494: A dampened kite string and flown the kite in a storm-threatened sky . A succession of sparks jumping from the key to the back of his hand showed that lightning was indeed electrical in nature. He also explained the apparently paradoxical behavior of the Leyden jar as a device for storing large amounts of electrical charge in terms of electricity consisting of both positive and negative charges. In 1775, Hugh Williamson reported
1130-425: A large lightning cloud may be as high as 100 MV and have discharge energies as great as 250 kWh. The field strength is greatly affected by nearby conducting objects, and it is particularly intense when it is forced to curve around sharply pointed objects. This principle is exploited in the lightning conductor , the sharp spike of which acts to encourage the lightning strike to develop there, rather than to
1243-402: A millimetre per second, the electric field that drives them itself propagates at close to the speed of light , enabling electrical signals to pass rapidly along wires. Current causes several observable effects, which historically were the means of recognising its presence. That water could be decomposed by the current from a voltaic pile was discovered by Nicholson and Carlisle in 1800,
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#17327903477051356-553: A more reliable source of electrical energy than the electrostatic machines previously used. The recognition of electromagnetism , the unity of electric and magnetic phenomena, is due to Hans Christian Ørsted and André-Marie Ampère in 1819–1820. Michael Faraday invented the electric motor in 1821, and Georg Ohm mathematically analysed the electrical circuit in 1827. Electricity and magnetism (and light) were definitively linked by James Clerk Maxwell , in particular in his " On Physical Lines of Force " in 1861 and 1862. While
1469-425: A positive current is defined as having the same direction of flow as any positive charge it contains, or to flow from the most positive part of a circuit to the most negative part. Current defined in this manner is called conventional current . The motion of negatively charged electrons around an electric circuit , one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of
1582-420: A positive or negative electric charge produces an electric field . The motion of electric charges is an electric current and produces a magnetic field . In most applications, Coulomb's law determines the force acting on an electric charge. Electric potential is the work done to move an electric charge from one point to another within an electric field, typically measured in volts . Electricity plays
1695-891: A practical generator, but it showed the possibility of generating electric power using magnetism, a possibility that would be taken up by those that followed on from his work. An electric circuit is an interconnection of electric components such that electric charge is made to flow along a closed path (a circuit), usually to perform some useful task. The components in an electric circuit can take many forms, which can include elements such as resistors , capacitors , switches , transformers and electronics . Electronic circuits contain active components , usually semiconductors , and typically exhibit non-linear behaviour, requiring complex analysis. The simplest electric components are those that are termed passive and linear : while they may temporarily store energy, they contain no sources of it, and exhibit linear responses to stimuli. The resistor
1808-406: A process now known as electrolysis . Their work was greatly expanded upon by Michael Faraday in 1833. Current through a resistance causes localised heating, an effect James Prescott Joule studied mathematically in 1840. One of the most important discoveries relating to current was made accidentally by Hans Christian Ørsted in 1820, when, while preparing a lecture, he witnessed the current in
1921-471: A rapidly changing one. Electric power is the rate at which electric energy is transferred by an electric circuit . The SI unit of power is the watt , one joule per second . Electric power, like mechanical power , is the rate of doing work , measured in watts , and represented by the letter P . The term wattage is used colloquially to mean "electric power in watts." The electric power in watts produced by an electric current I consisting of
2034-489: A resistance is directly proportional to the potential difference across it. The resistance of most materials is relatively constant over a range of temperatures and currents; materials under these conditions are known as 'ohmic'. The ohm , the unit of resistance, was named in honour of Georg Ohm , and is symbolised by the Greek letter Ω. 1 Ω is the resistance that will produce a potential difference of one volt in response to
2147-595: A running total of the electric energy delivered to a customer. Unlike fossil fuels , electricity is a low entropy form of energy and can be converted into motion or many other forms of energy with high efficiency. Electronics deals with electrical circuits that involve active electrical components such as vacuum tubes , transistors , diodes , sensors and integrated circuits , and associated passive interconnection technologies. The nonlinear behaviour of active components and their ability to control electron flows makes digital switching possible, and electronics
2260-431: A scientific curiosity into an essential tool for modern life. In 1887, Heinrich Hertz discovered that electrodes illuminated with ultraviolet light create electric sparks more easily. In 1905, Albert Einstein published a paper that explained experimental data from the photoelectric effect as being the result of light energy being carried in discrete quantized packets, energising electrons. This discovery led to
2373-575: A series of experiments to the Royal Society on the shocks delivered by the electric eel ; that same year the surgeon and anatomist John Hunter described the structure of the fish's electric organs . In 1791, Luigi Galvani published his discovery of bioelectromagnetics , demonstrating that electricity was the medium by which neurons passed signals to the muscles. Alessandro Volta 's battery, or voltaic pile , of 1800, made from alternating layers of zinc and copper, provided scientists with
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#17327903477052486-515: A series of observations on static electricity around 600 BCE, from which he believed that friction rendered amber magnetic , in contrast to minerals such as magnetite , which needed no rubbing. Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. According to a controversial theory, the Parthians may have had knowledge of electroplating , based on
2599-598: A set of equations that could unambiguously describe the interrelationship between electric field, magnetic field, electric charge, and electric current. He could moreover prove that in a vacuum such a wave would travel at the speed of light , and thus light itself was a form of electromagnetic radiation. Maxwell's equations , which unify light, fields, and charge are one of the great milestones of theoretical physics. Mediterranean Sea For other countries, click here . The Mediterranean Sea ( / ˌ m ɛ d ɪ t ə ˈ r eɪ n i ən / MED -ih-tə- RAY -nee-ən )
2712-477: A solid crystal (such as a germanium crystal) to detect a radio signal by the contact junction effect. In a solid-state component, the current is confined to solid elements and compounds engineered specifically to switch and amplify it. Current flow can be understood in two forms: as negatively charged electrons , and as positively charged electron deficiencies called holes . These charges and holes are understood in terms of quantum physics. The building material
2825-511: A wire disturbing the needle of a magnetic compass. He had discovered electromagnetism , a fundamental interaction between electricity and magnetics. The level of electromagnetic emissions generated by electric arcing is high enough to produce electromagnetic interference , which can be detrimental to the workings of adjacent equipment. In engineering or household applications, current is often described as being either direct current (DC) or alternating current (AC). These terms refer to how
2938-448: A wire suspended from a pivot above the magnet and dipped into the mercury. The magnet exerted a tangential force on the wire, making it circle around the magnet for as long as the current was maintained. Experimentation by Faraday in 1831 revealed that a wire moving perpendicular to a magnetic field developed a potential difference between its ends. Further analysis of this process, known as electromagnetic induction , enabled him to state
3051-402: A wire. The informal term static electricity refers to the net presence (or 'imbalance') of charge on a body, usually caused when dissimilar materials are rubbed together, transferring charge from one to the other. Charge can be measured by a number of means, an early instrument being the gold-leaf electroscope , which although still in use for classroom demonstrations, has been superseded by
3164-619: Is a calque of the Latin name, from μέσος ( mésos , "in the middle") and γήινος ( gḗinos , "of the earth"), from γῆ ( gê , "land, earth"). The original meaning may have been 'the sea in the middle of the earth', rather than 'the sea enclosed by land'. Ancient Iranians called it the "Roman Sea", and in Classical Persian texts , it was called Daryāy-e Rōm (دریای روم), which may be from Middle Persian form, Zrēh ī Hrōm (𐭦𐭫𐭩𐭤 𐭩 𐭤𐭫𐭥𐭬). The Carthaginians called it
3277-584: Is a scalar quantity . That is, it has only magnitude and not direction. It may be viewed as analogous to height : just as a released object will fall through a difference in heights caused by a gravitational field, so a charge will 'fall' across the voltage caused by an electric field. As relief maps show contour lines marking points of equal height, a set of lines marking points of equal potential (known as equipotentials ) may be drawn around an electrostatically charged object. The equipotentials cross all lines of force at right angles. They must also lie parallel to
3390-767: Is a sea connected to the Atlantic Ocean , surrounded by the Mediterranean Basin and almost completely enclosed by land: on the east by the Levant in West Asia , on the north by Anatolia in West Asia and Southern Europe , on the south by North Africa , and on the west almost by the Morocco–Spain border . The Mediterranean has played a central role in the history of Western civilization . Geological evidence indicates that around 5.9 million years ago,
3503-411: Is a vector field . The study of electric fields created by stationary charges is called electrostatics . The field may be visualised by a set of imaginary lines whose direction at any point is the same as that of the field. This concept was introduced by Faraday, whose term ' lines of force ' still sometimes sees use. The field lines are the paths that a point positive charge would seek to make as it
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3616-452: Is an important difference. Gravity always acts in attraction, drawing two masses together, while the electric field can result in either attraction or repulsion. Since large bodies such as planets generally carry no net charge, the electric field at a distance is usually zero. Thus gravity is the dominant force at distance in the universe, despite being much weaker. An electric field generally varies in space, and its strength at any one point
3729-401: Is charged by the glass rod, and the other by an amber rod, the two balls are found to attract each other. These phenomena were investigated in the late eighteenth century by Charles-Augustin de Coulomb , who deduced that charge manifests itself in two opposing forms. This discovery led to the well-known axiom: like-charged objects repel and opposite-charged objects attract . The force acts on
3842-473: Is defined as negative, and that by protons is positive. Before these particles were discovered, Benjamin Franklin had defined a positive charge as being the charge acquired by a glass rod when it is rubbed with a silk cloth. A proton by definition carries a charge of exactly 1.602 176 634 × 10 coulombs . This value is also defined as the elementary charge . No object can have a charge smaller than
3955-483: Is defined as the force (per unit charge) that would be felt by a stationary, negligible charge if placed at that point. The conceptual charge, termed a ' test charge ', must be vanishingly small to prevent its own electric field disturbing the main field and must also be stationary to prevent the effect of magnetic fields . As the electric field is defined in terms of force , and force is a vector , having both magnitude and direction , it follows that an electric field
4068-531: Is integral to applications spanning transport , heating , lighting , communications , and computation , making it the foundation of modern industrial society. Long before any knowledge of electricity existed, people were aware of shocks from electric fish . Ancient Egyptian texts dating from 2750 BCE described them as the "protectors" of all other fish. Electric fish were again reported millennia later by ancient Greek , Roman and Arabic naturalists and physicians . Several ancient writers, such as Pliny
4181-582: Is known as al-Baḥr [al-Abyaḍ] al-Mutawassiṭ ( البحر [الأبيض] المتوسط ) 'the [White] Middle Sea'. In Islamic and older Arabic literature, it was Baḥr al-Rūm ( بحر الروم ) or al- Baḥr al-Rūmī ( بحر الرومي ) 'the Sea of the Romans' or 'the Roman Sea' or Baḥr al-šām ( بحر الشام ) or al-Baḥr al-šāmī ( البحر الشامي ) ("the Sea of Syria"). At first, that name referred only to the eastern Mediterranean, but
4294-406: Is mediated by the magnetic field each current produces and forms the basis for the international definition of the ampere . This relationship between magnetic fields and currents is extremely important, for it led to Michael Faraday's invention of the electric motor in 1821. Faraday's homopolar motor consisted of a permanent magnet sitting in a pool of mercury . A current was allowed through
4407-415: Is most often a crystalline semiconductor . Solid-state electronics came into its own with the emergence of transistor technology. The first working transistor, a germanium -based point-contact transistor , was invented by John Bardeen and Walter Houser Brattain at Bell Labs in 1947, followed by the bipolar junction transistor in 1948. By modern convention, the charge carried by electrons
4520-403: Is perhaps the simplest of passive circuit elements: as its name suggests, it resists the current through it, dissipating its energy as heat. The resistance is a consequence of the motion of charge through a conductor: in metals, for example, resistance is primarily due to collisions between electrons and ions. Ohm's law is a basic law of circuit theory , stating that the current passing through
4633-531: Is subjected to transients , such as when first energised. The concept of the electric field was introduced by Michael Faraday . An electric field is created by a charged body in the space that surrounds it, and results in a force exerted on any other charges placed within the field. The electric field acts between two charges in a similar manner to the way that the gravitational field acts between two masses , and like it, extends towards infinity and shows an inverse square relationship with distance. However, there
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4746-406: Is termed the inductance . The unit of inductance is the henry , named after Joseph Henry , a contemporary of Faraday. One henry is the inductance that will induce a potential difference of one volt if the current through it changes at a rate of one ampere per second. The inductor's behaviour is in some regards converse to that of the capacitor: it will freely allow an unchanging current, but opposes
4859-415: Is the farad , named after Michael Faraday , and given the symbol F : one farad is the capacitance that develops a potential difference of one volt when it stores a charge of one coulomb. A capacitor connected to a voltage supply initially causes a current as it accumulates charge; this current will however decay in time as the capacitor fills, eventually falling to zero. A capacitor will therefore not permit
4972-529: Is therefore 0 at all places inside the body. This is the operating principal of the Faraday cage , a conducting metal shell which isolates its interior from outside electrical effects. The principles of electrostatics are important when designing items of high-voltage equipment. There is a finite limit to the electric field strength that may be withstood by any medium. Beyond this point, electrical breakdown occurs and an electric arc causes flashover between
5085-409: Is usually measured in volts , and one volt is the potential for which one joule of work must be expended to bring a charge of one coulomb from infinity. This definition of potential, while formal, has little practical application, and a more useful concept is that of electric potential difference , and is the energy required to move a unit charge between two specified points. An electric field has
5198-536: Is widely used in information processing , telecommunications , and signal processing . Interconnection technologies such as circuit boards , electronics packaging technology, and other varied forms of communication infrastructure complete circuit functionality and transform the mixed components into a regular working system . Today, most electronic devices use semiconductor components to perform electron control. The underlying principles that explain how semiconductors work are studied in solid state physics , whereas
5311-514: The Black Sea . In Persian, the name was translated as Baḥr-i Safīd , which was also used in later Ottoman Turkish . Similarly, in 19th century Greek, the name was Άσπρη Θάλασσα ( áspri thálassa ; "white sea"). According to Johann Knobloch, in classical antiquity , cultures in the Levant used colours to refer to the cardinal points: black referred to the north (explaining the name Black Sea ), yellow or blue to east, red to south (e.g.,
5424-740: The Italian Lakes (Po). While the Mediterranean watershed is bordered by other river basins in Europe, it is essentially bordered by endorheic basins or deserts elsewhere. The following countries are in the Mediterranean drainage basin while not having a coastline on the Mediterranean Sea: The following countries have a coastline on the Mediterranean Sea: Several other territories also border
5537-735: The Italian city-states like Amalfi and Genoa before the Crusades, according to the Cairo Geniza documents. A document dated 996 mentions Amalfian merchants living in Cairo . Another letter states that the Genoese had traded with Alexandria . The caliph al-Mustansir had allowed Amalfian merchants to reside in Jerusalem about 1060 in place of the Latin hospice . The Crusades led to
5650-721: The Neo-Latin word electricus ("of amber" or "like amber", from ἤλεκτρον, elektron , the Greek word for "amber") to refer to the property of attracting small objects after being rubbed. This association gave rise to the English words "electric" and "electricity", which made their first appearance in print in Thomas Browne 's Pseudodoxia Epidemica of 1646. Isaac Newton made early investigations into electricity, with an idea of his written down in his book Opticks arguably
5763-783: The Punic Wars in the 3rd and 2nd centuries BC, the Roman Republic defeated the Carthaginians to become the preeminent power in the Mediterranean. When Augustus founded the Roman Empire , the Romans referred to the Mediterranean as Mare Nostrum ("Our Sea"). For the next 400 years, the Roman Empire completely controlled the Mediterranean Sea and virtually all its coastal regions from Gibraltar to
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#17327903477055876-641: The Red Sea ) and white to west. That would explain the Bulgarian Byalo More , the Turkish Akdeniz , and the Arab nomenclature described above, lit. "White Sea". Major ancient civilizations were located around the Mediterranean. The sea provided routes for trade, colonization, and war, as well as food (from fishing and the gathering of other seafood) for numerous communities throughout
5989-559: The Roman Empire , Mare Nostrum ("Our Sea"). The term Mare Mediterrāneum appears later: Solinus apparently used this in the 3rd century, but the earliest extant witness to it is in the 6th century, in Isidore of Seville . It means 'in the middle of land, inland' in Latin , a compound of medius ("middle"), terra ("land, earth"), and -āneus ("having the nature of"). The modern Greek name Μεσόγειος Θάλασσα ( mesógeios ; "inland")
6102-423: The electromagnetic force , one of the four fundamental forces of nature. Experiment has shown charge to be a conserved quantity , that is, the net charge within an electrically isolated system will always remain constant regardless of any changes taking place within that system. Within the system, charge may be transferred between bodies, either by direct contact, or by passing along a conducting material, such as
6215-522: The quantum revolution. Einstein was awarded the Nobel Prize in Physics in 1921 for "his discovery of the law of the photoelectric effect". The photoelectric effect is also employed in photocells such as can be found in solar panels . The first solid-state device was the " cat's-whisker detector " first used in the 1900s in radio receivers. A whisker-like wire is placed lightly in contact with
6328-452: The strong interaction , but unlike that force it operates over all distances. In comparison with the much weaker gravitational force , the electromagnetic force pushing two electrons apart is 10 times that of the gravitational attraction pulling them together. Charge originates from certain types of subatomic particles , the most familiar carriers of which are the electron and proton . Electric charge gives rise to and interacts with
6441-528: The "Syrian Sea". In ancient Syrian texts, Phoenician epics and in the Hebrew Bible , it was primarily known as the "Great Sea", הים הגדול HaYam HaGadol , ( Numbers ; Book of Joshua ; Ezekiel ) or simply as "The Sea" ( 1 Kings ). However, it has also been called the "Hinder Sea" because of its location on the west coast of the region of Syria or the Holy Land (and therefore behind a person facing
6554-579: The 16th century and also maintained naval bases in southern France (1543–1544), Algeria and Tunisia. Barbarossa , the Ottoman captain is a symbol of this domination with the victory of the Battle of Preveza (1538). The Battle of Djerba (1560) marked the apex of Ottoman naval domination in the eastern Mediterranean. As the naval prowess of the European powers increased, they confronted Ottoman expansion in
6667-541: The 17th and 18th centuries. The development of the theory of electromagnetism in the 19th century marked significant progress, leading to electricity's industrial and residential application by electrical engineers by the century's end. This rapid expansion in electrical technology at the time was the driving force behind the Second Industrial Revolution , with electricity's versatility driving transformations in both industry and society. Electricity
6780-545: The 1936 discovery of the Baghdad Battery , which resembles a galvanic cell , though it is uncertain whether the artifact was electrical in nature. Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert wrote De Magnete , in which he made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber. He coined
6893-524: The 7th century, and with it the religion of Islam , which soon swept across from the east; at its greatest extent, the Arabs, under the Umayyads , controlled most of the Mediterranean region and left a lasting footprint on its eastern and southern shores. A variety of foodstuffs, spices and crops were introduced to the western Mediterranean's Spain and Sicily during Arab rule, via the commercial networks of
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#17327903477057006-834: The Atlantic via the Strait of Gibraltar —the narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates the Iberian Peninsula in Europe from Morocco in Africa —is only 14 km (9 mi) wide. The Mediterranean Sea encompasses a vast number of islands , some of them of volcanic origin. The two largest islands, in both area and population, are Sicily and Sardinia . The Mediterranean Sea has an average depth of 1,500 m (4,900 ft) and
7119-656: The Elder and Scribonius Largus , attested to the numbing effect of electric shocks delivered by electric catfish and electric rays , and knew that such shocks could travel along conducting objects. Patients with ailments such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber , could be rubbed with cat's fur to attract light objects like feathers. Thales of Miletus made
7232-655: The Islamic world. These include sugarcane, rice, cotton, alfalfa, oranges, lemons, apricots, spinach, eggplants, carrots, saffron and bananas. The Arabs also continued extensive cultivation and production of olive oil (the Spanish words for 'oil' and 'olive'— aceite and aceituna , respectively—are derived from the Arabic al-zait , meaning 'olive juice'), and pomegranates (the heraldic symbol of Granada) from classical Greco-Roman times. The Arab invasions disrupted
7345-602: The Levant, being the only state in history to ever do so, being given the nickname "Roman Lake". The Western Roman Empire collapsed around 476 AD. The east was again dominant as Roman power lived on in the Byzantine Empire formed in the 4th century from the eastern half of the Roman Empire . Though the Eastern Roman Empire would continue to hold almost all of the Mediterranean, another power arose in
7458-852: The Mediterranean Sea is the Nile , which takes its sources in equatorial Africa. The basin of the Nile constitutes about two-thirds of the Mediterranean drainage basin and encompasses areas as high as the Ruwenzori Mountains . Among other important rivers in Africa, are the Moulouya and the Chelif , both on the north side of the Atlas Mountains . In Asia, are the Ceyhan and Seyhan , both on
7571-612: The Mediterranean Sea to the Red Sea without ship lock, because the water level is essentially the same. The westernmost point of the Mediterranean is located at the transition from the Alborán Sea to the Strait of Gibraltar, the easternmost point is on the coast of the Gulf of Iskenderun in southeastern Turkey. The northernmost point of the Mediterranean is on the coast of the Gulf of Trieste near Monfalcone in northern Italy while
7684-525: The Mediterranean towards East Africa and Asia. This led to a preference for the Mediterranean countries and their ports like Trieste with direct connections to Central and Eastern Europe experienced a rapid economic rise. In the 20th century, the 1st and 2nd World Wars as well as the Suez Crisis and the Cold War led to a shift of trade routes to the European northern ports, which changed again towards
7797-516: The Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago. The Mediterranean Sea covers an area of about 2,500,000 km (970,000 sq mi), representing 0.7% of the global ocean surface, but its connection to
7910-700: The ages. The earliest advanced civilizations in the Mediterranean were the Egyptians and the Minoans , who traded extensively with each other. Other notable civilizations that appeared somewhat later are the Hittites and other Anatolian peoples , the Phoenicians , and Mycenean Greece . Around 1200 BC the eastern Mediterranean was greatly affected by the Bronze Age Collapse , which resulted in
8023-528: The area as generic Mediterranean Sea, in the Western Basin. It does not recognize the label Sea of Sardinia . Note 2: Thracian Sea and Myrtoan Sea are seas that are part of the Aegean Sea . Note 3: The Black Sea is not considered part of it. The International Hydrographic Organization defines the limits of the Mediterranean Sea as follows: Stretching from the Strait of Gibraltar in
8136-408: The beginning of the field theory of the electric force. Further work was conducted in the 17th and early 18th centuries by Otto von Guericke , Robert Boyle , Stephen Gray and C. F. du Fay . Later in the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a metal key to the bottom of
8249-419: The building it serves to protect. The concept of electric potential is closely linked to that of the electric field. A small charge placed within an electric field experiences a force, and to have brought that charge to that point against the force requires work . The electric potential at any point is defined as the energy required to bring a unit test charge from an infinite distance slowly to that point. It
8362-426: The charged particles themselves, hence charge has a tendency to spread itself as evenly as possible over a conducting surface. The magnitude of the electromagnetic force, whether attractive or repulsive, is given by Coulomb's law , which relates the force to the product of the charges and has an inverse-square relation to the distance between them. The electromagnetic force is very strong, second only in strength to
8475-450: The charged parts. Air, for example, tends to arc across small gaps at electric field strengths which exceed 30 kV per centimetre. Over larger gaps, its breakdown strength is weaker, perhaps 1 kV per centimetre. The most visible natural occurrence of this is lightning , caused when charge becomes separated in the clouds by rising columns of air, and raises the electric field in the air to greater than it can withstand. The voltage of
8588-411: The current varies in time. Direct current, as produced by example from a battery and required by most electronic devices, is a unidirectional flow from the positive part of a circuit to the negative. If, as is most common, this flow is carried by electrons, they will be travelling in the opposite direction. Alternating current is any current that reverses direction repeatedly; almost always this takes
8701-644: The deepest recorded point is 5,109 ± 1 m (16,762 ± 3 ft) in the Calypso Deep in the Ionian Sea . It lies between latitudes 30° and 46° N and longitudes 6° W and 36° E . Its west–east length, from the Strait of Gibraltar to the Gulf of Alexandretta , on the southeastern coast of Turkey , is about 4,000 kilometres (2,500 mi). The north–south length varies greatly between different shorelines and whether only straight routes are considered. Also including longitudinal changes,
8814-516: The design and construction of electronic circuits to solve practical problems are part of electronics engineering . Faraday's and Ampère's work showed that a time-varying magnetic field created an electric field, and a time-varying electric field created a magnetic field. Thus, when either field is changing in time, a field of the other is always induced. These variations are an electromagnetic wave . Electromagnetic waves were analysed theoretically by James Clerk Maxwell in 1864. Maxwell developed
8927-512: The destruction of many cities and trade routes. The most notable Mediterranean civilizations in classical antiquity were the Greek city states and the Phoenicians , both of which extensively colonized the coastlines of the Mediterranean. Darius I of Persia , who conquered Ancient Egypt, built a canal linking the Red Sea to the Nile, and thus the Mediterranean. Darius's canal was wide enough for two triremes to pass each other with oars extended and required four days to traverse. Following
9040-478: The early 19th century had seen rapid progress in electrical science, the late 19th century would see the greatest progress in electrical engineering . Through such people as Alexander Graham Bell , Ottó Bláthy , Thomas Edison , Galileo Ferraris , Oliver Heaviside , Ányos Jedlik , William Thomson, 1st Baron Kelvin , Charles Algernon Parsons , Werner von Siemens , Joseph Swan , Reginald Fessenden , Nikola Tesla and George Westinghouse , electricity turned from
9153-596: The east), which is sometimes translated as "Western Sea". Another name was the "Sea of the Philistines ", ( Book of Exodus ), from the people inhabiting a large portion of its shores near the Israelites . In Modern Hebrew , it is called הים התיכון HaYam HaTikhon 'the Middle Sea'. In Classic Persian texts was called Daryāy-e Šām (دریای شام) "The Western Sea" or "Syrian Sea". In Modern Standard Arabic , it
9266-427: The effect was reciprocal: a current exerts a force on a magnet, and a magnetic field exerts a force on a current. The phenomenon was further investigated by Ampère , who discovered that two parallel current-carrying wires exerted a force upon each other: two wires conducting currents in the same direction are attracted to each other, while wires containing currents in opposite directions are forced apart. The interaction
9379-448: The electronic electrometer . The movement of electric charge is known as an electric current , the intensity of which is usually measured in amperes . Current can consist of any moving charged particles; most commonly these are electrons, but any charge in motion constitutes a current. Electric current can flow through some things, electrical conductors , but will not flow through an electrical insulator . By historical convention,
9492-416: The electrons. However, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive-to-negative convention is widely used to simplify this situation. The process by which electric current passes through a material is termed electrical conduction , and its nature varies with that of the charged particles and
9605-428: The elementary charge, and any amount of charge an object may carry is a multiple of the elementary charge. An electron has an equal negative charge, i.e. −1.602 176 634 × 10 coulombs . Charge is possessed not just by matter , but also by antimatter , each antiparticle bearing an equal and opposite charge to its corresponding particle. The presence of charge gives rise to an electrostatic force: charges exert
9718-555: The entire Mediterranean. Once, most of the trade between Western Europe and the East was passing through the region , but after the 1490s the development of a sea route to the Indian Ocean allowed the importation of Asian spices and other goods through the Atlantic ports of western Europe. The sea remained strategically important. British mastery of Gibraltar ensured their influence in Africa and Southwest Asia. Especially after
9831-672: The flourishing of trade between Europe and the outremer region. Genoa, Venice and Pisa created colonies in regions controlled by the Crusaders and came to control the trade with the Orient. These colonies also allowed them to trade with the Eastern world. Though the fall of the Crusader states and attempts at banning of trade relations with Muslim states by the Popes temporarily disrupted
9944-495: The form of a sine wave . Alternating current thus pulses back and forth within a conductor without the charge moving any net distance over time. The time-averaged value of an alternating current is zero, but it delivers energy in first one direction, and then the reverse. Alternating current is affected by electrical properties that are not observed under steady state direct current, such as inductance and capacitance . These properties however can become important when circuitry
10057-436: The immediate coastline on all sides of the Mediterranean tends to have strong maritime moderation. The sea was an important route for merchants and travellers of ancient times, facilitating trade and cultural exchange between the peoples of the region. The history of the Mediterranean region is crucial to understanding the origins and development of many modern societies. The Roman Empire maintained nautical hegemony over
10170-691: The major ranges bordering Southern Europe. Total annual precipitation is significantly higher on the European part of the Mediterranean basin, especially near the Alps (the 'water tower of Europe') and other high mountain ranges. As a consequence, the river discharges of the Rhône and Po are similar to that of the Nile, despite the latter having a much larger basin. These are the only three rivers with an average discharge of over 1,000 m /s (35,000 cu ft/s). Among large natural fresh bodies of water are Lake Victoria (Nile basin), Lake Geneva (Rhône), and
10283-400: The material through which they are travelling. Examples of electric currents include metallic conduction, where electrons flow through a conductor such as metal, and electrolysis , where ions (charged atoms ) flow through liquids, or through plasmas such as electrical sparks. While the particles themselves can move quite slowly, sometimes with an average drift velocity only fractions of
10396-521: The migrants and arrest the traffickers of immigrants. In 2015, more than one million migrants crossed the Mediterranean Sea into Europe. Italy was particularly affected by the European migrant crisis . Since 2013, over 700,000 migrants have landed in Italy, mainly sub-Saharan Africans. The Mediterranean Sea connects: The 163 km (101 mi) long artificial Suez Canal in the southeast connects
10509-490: The naval battles of Abukir (1799, Battle of the Nile ) and Trafalgar (1805), the British had for a long time strengthened their dominance in the Mediterranean. Wars included Naval warfare in the Mediterranean during World War I and Mediterranean theatre of World War II . With the opening of the lockless Suez Canal in 1869, the flow of trade between Europe and Asia changed fundamentally. The fastest route now led through
10622-428: The number of drowned refugees in the region as a direct result of the policies. An Azerbaijani official described the sea as "a burial ground ... where people die". Following the 2013 Lampedusa migrant shipwreck , the Italian government decided to strengthen the national system for the patrolling of the Mediterranean Sea by authorising " Operation Mare Nostrum ", a military and humanitarian mission in order to rescue
10735-428: The principle, now known as Faraday's law of induction , that the potential difference induced in a closed circuit is proportional to the rate of change of magnetic flux through the loop. Exploitation of this discovery enabled him to invent the first electrical generator in 1831, in which he converted the mechanical energy of a rotating copper disc to electrical energy. Faraday's disc was inefficient and of no use as
10848-613: The region when the Battle of Lepanto (1571) checked the power of the Ottoman Navy . This was the last naval battle to be fought primarily between galleys . The Barbary pirates of Northwest Africa preyed on Christian shipping and coastlines in the Western Mediterranean Sea. According to Robert Davis, from the 16th to 19th centuries, pirates captured 1 million to 1.25 million Europeans as slaves. The development of oceanic shipping began to affect
10961-468: The sea for centuries and is the only state to have ever controlled all of its coast. The countries surrounding the Mediterranean and its marginal seas in clockwise order are Spain , France , Monaco , Italy , Slovenia , Croatia , Bosnia and Herzegovina , Montenegro , Albania , Greece , Turkey , Syria , Lebanon , Israel , Palestine ( Gaza Strip ), Egypt , Libya , Tunisia , Algeria , and Morocco ; Cyprus and Malta are island countries in
11074-554: The sea. In addition, Northern Cyprus ( de facto state ) and two overseas territories of the United Kingdom ( Akrotiri and Dhekelia , and Gibraltar ) also have coastlines along the Mediterranean Sea. The drainage basin encompasses a large number of other countries, the Nile being the longest river ending in the Mediterranean Sea. The Ancient Egyptians called the Mediterranean Wadj-wr/Wadj-Wer/Wadj-Ur. This term (literally "great green")
11187-427: The set of physical phenomena associated with the presence and motion of matter possessing an electric charge . Electricity is related to magnetism , both being part of the phenomenon of electromagnetism , as described by Maxwell's equations . Common phenomena are related to electricity, including lightning , static electricity , electric heating , electric discharges and many others. The presence of either
11300-476: The shortest shipping route between the multinational Gulf of Trieste and the Libyan coastline of the Gulf of Sidra is about 1,900 kilometres (1,200 mi). The water temperatures are mild in winter and warm in summer and give name to the Mediterranean climate type due to the majority of precipitation falling in the cooler months. Its southern and eastern coastlines are lined with hot deserts not far inland, but
11413-736: The south side of the Taurus Mountains . In Europe, the largest basins are those of the Rhône , Ebro , Po , and Maritsa . The basin of the Rhône is the largest and extends up as far north as the Jura Mountains , encompassing areas even on the north side of the Alps . The basins of the Ebro, Po, and Maritsa, are respectively south of the Pyrenees , Alps, and Balkan Mountains , which are
11526-584: The southern ports through European integration, the activation of the Silk Road and free world trade. In 2013, the Maltese president described the Mediterranean Sea as a "cemetery" due to the large number of migrants who drowned there after their boats capsized. European Parliament president Martin Schulz said in 2014 that Europe's migration policy "turned the Mediterranean into a graveyard", referring to
11639-599: The southernmost point is on the coast of the Gulf of Sidra near the Libyan town of El Agheila . Large islands in the Mediterranean include: The Alpine arc , which also has a great meteorological impact on the Mediterranean area, touches the Mediterranean in the west in the area around Nice . The typical Mediterranean climate has hot, dry summers and mild, rainy winters. Crops of the region include olives , grapes , oranges , tangerines , carobs and cork . The Mediterranean Sea includes 15 marginal seas : Note 1: The International Hydrographic Organization defines
11752-454: The special property that it is conservative , which means that the path taken by the test charge is irrelevant: all paths between two specified points expend the same energy, and thus a unique value for potential difference may be stated. The volt is so strongly identified as the unit of choice for measurement and description of electric potential difference that the term voltage sees greater everyday usage. For practical purposes, defining
11865-602: The term was later extended to the whole Mediterranean, it was also called Baḥr al-Maghrib ( بحر المغرب ) ("the Sea of the West"). A name that was used mainly for the western basin. In Turkish , it is the Akdeniz 'the White Sea'; in Ottoman, ﺁق دڭيز , which sometimes means only the Aegean Sea . The origin of the name is not clear, as it is not known in earlier Greek, Byzantine or Islamic sources. It may be to contrast with
11978-672: The trade in western Europe and brought it to a halt. However, the Norsemen developed the trade from Norway to the White Sea , while also trading in luxury goods from Spain and the Mediterranean. The Byzantines in the mid-8th century retook control of the area around the north-eastern part of the Mediterranean. Venetian ships from the 9th century armed themselves to counter the harassment by Arabs while concentrating trade of Asian goods in Venice. The Fatimids maintained trade relations with
12091-600: The trade relations between Western and Eastern Europe while disrupting trade routes with Eastern Asian Empires. This, however, had the indirect effect of promoting trade across the Caspian Sea . The export of grains from Egypt was re-routed towards the Eastern world . Products from East Asian empires, like silk and spices, were carried from Egypt under the Arab rule to ports like Venice and Constantinople by sailors and Jewish merchants. The Viking raids further disrupted
12204-649: The trade with the Orient, it however continued. Europe started to revive, however, as more organized and centralized states began to form in the later Middle Ages after the Renaissance of the 12th century . Ottoman power based in Anatolia continued to grow, and in 1453 extinguished the Byzantine Empire with the Conquest of Constantinople . Ottomans gained control of much of the eastern part sea in
12317-418: The two forces of nature then known. The force on the compass needle did not direct it to or away from the current-carrying wire, but acted at right angles to it. Ørsted's words were that "the electric conflict acts in a revolving manner." The force also depended on the direction of the current, for if the flow was reversed, then the force did too. Ørsted did not fully understand his discovery, but he observed
12430-417: The vector direction of the field is the line of greatest slope of potential, and where the equipotentials lie closest together. Ørsted's discovery in 1821 that a magnetic field existed around all sides of a wire carrying an electric current indicated that there was a direct relationship between electricity and magnetism. Moreover, the interaction seemed different from gravitational and electrostatic forces,
12543-657: The west to the entrances to the Dardanelles and the Suez Canal in the east, the Mediterranean Sea is bounded by the coasts of Europe, Africa, and Asia and is divided into two deep basins: The drainage basin of the Mediterranean Sea is particularly heterogeneous and extends much further than the Mediterranean region. Its size has been estimated between 4,000,000 and 5,500,000 km (1,500,000 and 2,100,000 sq mi), depending on whether non-active parts (deserts) are included or not. The longest river ending in
12656-543: Was forced to move within the field; they are however an imaginary concept with no physical existence, and the field permeates all the intervening space between the lines. Field lines emanating from stationary charges have several key properties: first, that they originate at positive charges and terminate at negative charges; second, that they must enter any good conductor at right angles, and third, that they may never cross nor close in on themselves. A hollow conducting body carries all its charge on its outer surface. The field
12769-734: Was the name given by the Ancient Egyptians to the semi-solid, semi-aquatic region characterized by papyrus forests to the north of the cultivated Nile delta, and, by extension, the sea beyond. The Ancient Greeks called the Mediterranean simply ἡ θάλασσα ( hē thálassa ; "the Sea") or sometimes ἡ μεγάλη θάλασσα ( hē megálē thálassa ; "the Great Sea"), ἡ ἡμετέρα θάλασσα ( hē hēmetérā thálassa ; "Our Sea"), or ἡ θάλασσα ἡ καθ’ ἡμᾶς ( hē thálassa hē kath’hēmâs ; "the sea around us"). The Romans called it Mare Magnum ("Great Sea") or Mare Internum ("Internal Sea") and, starting with
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