Electricity (of Greek (electron) "amber ") is the generic term for all phenomena, which have their cause either in resting electrical charge or moved charge (rivers) as well as their electrical and magnetic fields. The carriers of the electrical charge are negatively charged electrons and positively charged protons and ions. Charges of the same name repel themselves, ungleichnamige charges tighten each other. Because of the reciprocal effect forces also a meaning comes to the electricity as source of energy. Electrical charges are the sources of the electrical field, moved charges the cause for magnetic field-electromagnetic waves (like e.g. Light) are excitations of the electromagnetic field and can after emergence independently of charge carriers in the area (when photons) spread, in addition, i.e. to move, they interact with subject.

Movement of electrical charge takes place in electrical conductors by movement of free electrons and in liquids by ion movement. With the solids one differentiates between leaders, nonconductors and semiconductors.

Electrical phenomena in nature

The probably most well-known and most spectacular natural occurrence of electricity is lightning. With lightning high electrostatic charges (triboelectricity), developed by friction in the thunderclouds, unload themselves. In the process of such an unloading both positive are moved as well as negative charges.

But electricity arises even in less spectacular form. Thus e.g. the data processing in the nervous system of organisms is based partially on electrical signals.

Different fish (e.g. the trembling skate and the Zitteraal) can develop high electrical tensions, in order to defend itself thereby. Turned around they succeed in by perception of electrical signals, which are released by the muscle movements of the fish, locating their booty.

Electricity in the everyday life

Colloquially by electricity usually electricity is understood. For the characterisation of electricity in the linguistic usage usually only of river or tension one speaks. This is wrong in many cases, since effects of electricity are to be explained only with common view from river and tension to. Thus for example piezoelectric lighter fuzes produce very high tensions (~1 kV), are however because of the small amperage almost innocuous. To it the example is similar with a car battery, which supplies a tension of 12 V, but comparatively high rivers produces.

In the today's everyday life electricity in the sense of electricity is hardly dispensable more, which humans usually only by losses of supply networks becomes again conscious. For over one century uses of electricity, like light, determine warmth and Kraft more and more the human life. A constantly growing meaning attains today electricity in communication and information technology.

Electricity has different effects depending upon strength on the human body. For the effect the strength of the flow is crucial in the unit A (ampere). Small flows are used for example for the promotion of healing processes in the electrical therapy or as pulse generators for the heart (cardiac pacemaker). Strong flows starting from approx. 50 mA can be dangerous and work deadly. The electrical shock pistol for example delivers several times strong electrical impulses to the victim and causes painful, not controllable muscle contractions. With sensitive persons breath paralyses and heart stop can occur. Such flows are also used, in order to kill humans purposefully, as this happens also with the electrical chair.

Treatment in the natural sciences

The different phenomena of the electricity are view articles in parts of physics and chemistry:

• Electrostatics: resting electrical charges, charge distributions and electrical fields of loaded bodies
• Electrodynamics: electromagnetic waves, electrical and magnetic fields, Potenziale and dynamics of electrically charged particles and objects
• Quantum electrodynamics: quantum-field-theoretical description of electromagnetism
• Solid-state physics: Behavior of electrical charges in leaders, semiconductors and nonconductors, as well as thermal, Pyro and piezoelectricity
• Electrochemistry: Connection between electrical and chemical procedures

Treatment in the engineering sciences

Electro-technology designates that range of the engineering science and technology, which with all aspects of the electricity is concerned. To it belong the electrical energy production, the transfer of energy as well as all kinds of their use. This reaches from the electrically operated machines over all kinds of electrical circuits for the tax, measuring, regulation and computer engineering up to the communications technology.

Electricity as sources of energy

The electricity computes itself as the product of electrical tension, amperage and length of time.

E=U \ cdot I \ cdot t

Production of electricity

See in addition independent article generation of current

With the production or also production of electricity different of the phenomena described above are used. The largest portion of the world-wide (electrical) power requirement is produced by generators in power stations. Different primary energy carriers are used. The used generators are identical from the basic principle. They use the electro-dynamic induction for separation of load and thus to the Spannungserzeugung.In batteries and accumulators electricity from chemical reactions are won. In gas cells electricity during a continuous process from chemical energy is won. The comparatively recent technology of the Photovoltaik uses with solar cells the photoelectric Effekt.In thermoelectric generators (e.g. isotopic batteries) electricity with thermocouples directly from heat energy is won. In the Thermoioni generator a hot metal surface emits electrons in the vacuum, which are caught by an electrode in small distance by filament emission. The magnetohydrodynamische generator (MHD generator) separates an ionized gas from a burn process, into its positive and negative particles, flowing fast between electrodes, with a magnetic field.

Transport of electricity

The transport of electricity is in most cases done via the movement of electrons in solids. For it lines from materials with a small resistivity (mostly metals) are used. Copper and silver belong to aluminum to the best leaders, also because of the smaller weight are partly used. From the electrical resistance of the lines line losses (losses of energy) result all the more highly are, the more highly the amperage and the longer and thinner the transportation line are. With higher tensions the same energy quantity can be transferred with smaller amperages.

The unavoidable losses in the case of transport can be reduced therefore by use of high tensions. Electrical high voltage transmission lines are operated e.g. with alternating voltages within the range of 10 kV to 380 kV. For the change of alternating voltages transformers are used. Since the energy, which is produced frequently in power stations, is generated partly quite far by the consumers, the energy transfer has a large influence on the efficiency of the overall system.

At present one tries to use superconductors for the transport of electricity in first pilot projects, since in these the electrons are transported almost without resistance.

Articles in category "Electricity"

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