Техническое чтение для энергетиков. Бухарова Г.П. - 23 стр.

UptoLike

ВУЗ: 

УлГТУ | Ульяновск

Составители: 

Рубрика: 

25
rubbed, it attracted and held minute light objects. However, he could not know that
amber was charged with electricity owing to the process of rubbing. Then Gilbert, the
English physicist, began the first systematic scientific research on electrical
phenomena. Rediscovered that various other substances possessed the property
similar to that of amber or, in other words, they generated electricity when they were
rubbed. He gave the name "electricity" to the phenomenon he was studying. He got
this word from the Greek "electrum" meaning "amber".
Many learned men of Europe began to use the new word "electricity" in their
conversation as they were engaged in research of their own. Scientists of Russia,
France and Italy made their contribution as well as the Englishmen and the Germans.
FROM THE HISTORY OF ELECTRICITY
There are two types of electricity, namely, electricity at rest or in a static
condition and electricity in motion, that is, the electric current. Both of them are made
up of electric charges, static charges being at rest, while electric current flows and
does work. Thus, they differ in their ability to serve mankind as well as in their
behaviour. Let us first turn our attention to static electricity. For a long time it was the
only electrical phenomenon to be observed by man. As previously mentioned at least
2,500 years ago, or so, the Greeks knew how to get electricity by rubbing substances.
However, the electricity to be obtained by rubbing objects cannot be used to light
lamps, to boil water, to run electric trains, and so on. It is usually very high in voltage
and difficult to control, besides it discharges in no time.
As early as 1753, Franklin made an important contribution to the science of
electricity. He was the first to prove that unlike charges are produced due to rubbing
dissimilar objects To show that the charges are unlike and opposite, he decided to call
the charge on the rubber– negative and that on the glass–positive.
In this connection one might remember the Russian academician V. V. Petrov.
He was the first to carry on experiments and observations on the electrification of
metals by rubbing them one against another. As a result he was the first scientist in
the world who solved that problem.
Who does not know that the first man to get the electric current was Volta after
whom the unit of electric pressure, the volt, was named? His discovery developed
out of Galvani's experiments with the frog. Galvani observed that the legs of a dead
frog jumped as a result of an electric charge. He tried his experiment several times
and every time he obtained the same result. He thought that electricity was generated
within the leg itself.
Volta began to carry on similar experiments and soon found that the electric
source was not within the frog's leg but was the result of the contact of both
dissimilar metals used during his observations. However, to carry on such
experiments was not an easy thing to do. He spent the next few years trying to invent
a source of continuous current. To increase the effect obtained with one pair of met-
als, Volta increased the number of these pairs. Thus the voltaic pile consisted of a
copper layer and a layer of zinc placed one above another with a layer of flannel

Страницы