The three-phase alternating current is generated by rotating fields traversing three windings suitably arranged.
Electrical distribution lines (EDF in France) generally consist of four three-phase conductors and neutral. The neutral is usually connected to ground through the distribution networks for reasons of safety and convenience.
The phase voltages and phase voltages: the voltages are measured between the neutral phases V, the voltage measured between the composite phases U. The measurement unit is the Volt.
The electric current chemical effects: there decompositions as it passes through certain liquids called electrolytes, which can be as acids, bases or salts or molten or in solution, usually in water.
The operation called electrolyte is in a vessel, in which the conductive blade is called the current reaches the positive electrode (input terminal) or anode, the other blade is the negative electrode (output terminal) or cathode.
In a solution of copper sulphate CuSO4 with a copper anode and a cathode any. (See example) In this example, forms a copper deposit on the cathode, but nothing has emerged on the anode. The color of the solution does not change: it impoverishes not in copper sulphate, notwithstanding the filing of the cathode. The anode gradually disappears. is that the ion SO4 after losing his office reacts to give copper sulphate which dissolves, and can be summarized as follows:
The applications of electrolysis are many, it is used for the industrial preparation of a large number of bodies (hydrogen, oxygen, chlorine, sodium, potassium chlorate, aluminum, copper, etc. ...
It also serves to deposit a layer of metal (copper, nickel, chromium, silver, gold) on an object for supporting any or mold. This is electroplating. We can preserve the iron from rust: simply the nickel. It can cover a body of a precious metal silver or gold plating.
The same phenomenon allows use in the refining of impure metals, copper for example.
See also: calculator of the duration of an operation of electrolysis
The science of electricity has gradually formed from simple observations of natural phenomena. Compass is the first application.
The
possibility of producing electricity at will was acquired only in the
seventeenth century (static machines of Guericke and Huygens), in the
early eighteenth century, the discovery of electricity helped to
classify the different "fluid" into two categories: the vitreous electricity (positive), the resinous electricity (negative).
In
the eighteenth century, the experiment is sufficiently developed so
that we can construct the first theories and experiments and
measurements more precise, spend qualitative to the quantitative
(Cavendish and Coulomb).
But static electricity that is produced, and that is the subject of research, can not get much progress. In 1800, the discovery of the stack (Volta) provides electric currents (dynamic power). So is the junction of two categories, electricity and magnetism into electromagnetism. Stringent laws are established (Ampere and Ohm, same year, 1827) and one discovers the induction currents (Foucault, 1850).
Parallel
to this research, a long series of observations and experiments on the
conductivity of electricity in gases led to the identification of the
phenomena of radiation. Thus
the rays are discovered successively positive (Goldstein), the cathode
rays (Hertz, J. Perrin, JJ Thomson, P. Lenard) and X-rays (Roentgen),
the latter paving the way for remarkable applications in both medicine knowledge of the constitution of matter.
Maxwell's equations allow the discovery of radio waves (Hertz), the source of radio engineering. So
was born the theory of Lorentz (1892-1895) where, at the microscopic
level, is associated with moving charges an electric field and magnetic
field.
The
work of Pierre Curie on symmetry of physical phenomena, by introducing
the concept of prediction, mark a turning point; his studies on
magnetism are continued and expanded by his student Paul Langevin. That's when that knowledge of the constitution of the atom states (N. Bohr) and Max Planck's quantum theory sets. Einstein
to explain the photoelectric effect, amounts to a granular conception
of electricity in 1925, Louis de Broglie operates a synthesis between
the wave and particle theories.
