Electricity

electricity (of Greek ήλεκτρο (electrical) „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 thatelectrical 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 sourcesthe electrical field, the cause for magnetic fields moved charges.Electromagnetic waves (like z. B. Light) are excitations of the electromagnetic field and can after emergence independently of charge carriers in the area (when photons) spread, D. h. move, they interact howeveralso 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.

Table of contents

electrical ones Phenomena in the nature

of lightnings were the first experience of humans with electricity

the probably most well-known and most spectacular natural occurrence of electricity are lightning. With lightning high electrostatic charges developed by friction in the thunderclouds unload themselves(Triboelectricity). 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 z is based. B. the data processing in the nervous system of organisms partially on electrical signals.

Different fish (z. B. 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

colloquial is understood by electricity usually electricity. For the characterisation of electricity in the linguistic usage usually only of river or tension one speaks. This is in many cases wrongly, there effects of electricity onlyduring common view from river and tension to to explain are. 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, the one tension of12 V supplies, 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 applications determineof electricity, like light, 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. Cruciallyfor the effect the strength of the flow is 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 off approx. 50mA 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, overTo 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:

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 belongthe electrical energy production, the transfer of energy as well as all kinds of their use. Dies reicht von den elektrisch betriebenen Maschinen über alle Arten elektrischer Schaltungen für die Steuer-, Mess-, Regelungs- und Computertechnik bis hin zur Nachrichtentechnik.

Electricity as source of energy

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

<math> E=U \ cdot I \ cdot t </math>

to production of electricity

see in addition independent article generation of current

with the production or also productionelectricity 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 for tension production.
In batteries and accumulators electricity from chemical reactions is 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 effect.
In thermoelectric generators (e.g. Isotopic batteries) electricity with thermocouples is won directly from heat energy.
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 happens in mostCases by 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. Throughthe electrical resistance of the lines line losses (losses of energy) develop 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 lossesin the case of transport can be reduced therefore by use of high tensions. Electrical high voltage transmission lines become z. B. with alternating voltages within the range of 10 kV to 380 kV operated. For the change of alternating voltages transformers are used. There the energy, which frequently in For power stations , partly quite far by the consumers is generated, has the energy transfer is produced a large influence on the efficiency of the overall system.

At present one tries to use those in first pilot projects superconductors for the transport of electricity, there in theseElectrons to be transported almost without resistance.

historical data

physical dimension

<math> Q = I \ cdot t< /math>
The smallest electrical charge is the elementary charge e (natural constant), the charge of an electron. It amounts to approx. 1,602 · 10 ,-19 C. The not freely observable quarks have still smaller, third-tough-lie to chargesof <math> \ frac {1} {3} e, \ frac {2} {3} e< /math>.
an ampere is the strength of a constant river, by two the parallel, straight-line, infinitely for a long time and in the vacuum in the distance of a meter ladder from each other arranged ofnegligibly small, circular cross section flowing, between these leaders per meter of leader length Kraft of 2 · 10 −7 Newton causes.
<math> U = R \ cdot I = \ frac {W} {Q} = \ frac {P} {I}< /math>
in the d.c. circuit:
<math> P = U \ cdot I </math>
In the alternating current circle:
<math> P = U \ cdot I \ cdot \ cos \ varphi< /math>
  • Effect work< math> [W]< /math> in a KW/H (kilowatt-hour),Wh (Watt hour), WG or joule
<math> W = P \ cdot \ delta t </math>
<math> Q = U \ cdot I \ cdot \ sin \ varphi< /math>
<math> S = U \ cdot I </math>
  • Blind work<math> [W_q]< /math> in Vars; Varh or kVarh
    illusory work <math> [W_s]< /math> in VAs; To VAh or kVAh

see also

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Wiktionary: Electricity - word origin, synonyms and translations
 

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