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25.11.2020 02:54 •  Английский язык

Перевести текст на русский язык TEXT 2. ELECTRIC CURRENTS AND THEIR PROPERTIES
Пояснения к тексту:
electromotive force – электродвижущая сила
wire – труба
direct current (d. c) – постоянный ток
alternating current (a. c.) – переменный ток
pulsating current – пульсирующий ток.
Conduction is the name normally given to a movement or flow of charges. The charges are usually electrons, but may also be ions when the conduction
takes place in gaseous or liquid conductors, in which the ions are mobile.
How does the current flow through a wire? A metal is made up of tiny
crystals which are visible under a microscope. A crystal is a regular and orderly arrangement of atoms. As it was explained, an atom is a complex particle in which tiny electrons move around nucleus. When the atoms are tightly
packed as they are in a metallic solid, some of the electrons move freely between the atoms. These are called free electrons. Ordinarily, the free electrons
move at random through the metal. There must be some driving force to
cause the electrons to move through the metal conductor. This driving force
tending to produce the motion of electrons through a circuit is called an electromotive force or e.m.f. that moves electric charges from one point in the
circuit to another.
When an electromotive force is applied to the ends of a wire the free electrons move in one direction. It is the movement of the free electrons in a conductor that induces an electric current. The greater the number of participating
electrons, the greater is the flow of current.
No one has ever seen analectic current. We only know of the existence of
a current by its effects. A current can heat a conductor, it can have a chemical
action when passing through a solution, or it can produce a magnetic effect. We
can measure currents by observing their heating, their chemical, or their magnetic effects.
There are some kinds of current, namely: a direct current (d. c, for short),
an alternating current (a. c.) a pulsating current.