.


:




:

































 

 

 

 


Resistance and Resistivity

Mikchail Lomonosov

Mikchail Lomonosov the greate Russian scientist and poet. He studied at the Slavonic - breek - Latin Academy in Moskow. Lomonosov founded our first university the Moskow University named after him. He taught chemistry and other subjec at the Academy of scienses. He formulated the main principles of one of the basic laws of physics the law of conservation of matter and mation. He asserted that all matter was made up of minute particles which the called elements and corpuscles. By corpuscles he meant compound particless consisting of simple particles - elements. Now we say molecules and atoms.

It is remarkable that the diference between the molecule and the atom made clear by Lomonosov was precisely formulated for the second time at a special international congress of chemists only a hundred years later. Lomonosov maintained that corpuscules and elements represent infinitely small bodies. Lomonosov was the first who gave the idea about absolute zero.

He developed his life to the development of Russian science and all that he did he did for his people and country.

Mikchail . - breek - . . . . , , . particless, - . .

, . , . , .

, , .

D.I. Mendeleyev

D.I. Mendeleyev the great Russian scientist was born in Tobolsk in 1834. He was the first to discover the law of dependence of the properties of the elements upon their atomic weights. Mendeleyev suggested system of classification in which the elements are arranged in the order of in increasing atomic weights. He published his famous periodic classification in 1869.

The main idea of the Periodic System is that of the atomic weights.He even described the properties of these elements no gaps are left now for undiscover elements.

With the Periodic Table at his disposal a chemist needh't learn all the properties of all the elements.

The Table is was and will be refered to and use a in Solving research problems of Industial importance.

.. 1834 . , . , . 1869 .

, weights.He undiscover .

needh't .

- .

 

Alexander Popov.

Radio was invented in Russia the worlds first receiver was built in 1835 by the great Russia scientist Alexander Popov.He demonstated a device called a storm indicators at meeting Scientist in St.Petermurg on May 7 1895. in 1896 he sent the words first wireless telegram over a distance of 250m. 7 May is marked was a radio day. Radio help us to maintain contact with ships with flying or a spacecraft.

.

1835 . , St.Petermurg 7 1895 . 1896 250. 7 . .

Benjamin franklin.

Franklin is acknowledged to be the founded of the theory of atmospheric electricity. He was the first to prove that the lighting electricity phenomenom. He finally invented a mean of protection against the disastrous effect of the. Franklin is known and respected all over the world not only as a sxientist but also as a citizen who did as much he could for the good of his country. Coming out in defence of the Afro-Americans Franklin declared slavery to be not only an evil from the social interest of America. He is to be one of the broadest as as one of the most creative minds of his time.

.

. , , . . sxientist, , , , . - . .

Semi-conductors

According to heir conductivity all materials are divided in to conductors insulators and semiconductors. Conductors allow electricity to pass through them insulators do not. The most common of them are metals (copper, aluminium, steel, ana others) carbon.

According to their resistivity conductors are divided in to two group the first includes material with low resistivity copper aluminium and others.

, . . (, , , .) .

.

Insulators

insulators materials have a very low conductivity. Insulators are divided into gaseous liquid solid.

The main gaseous insulator is air. Liquid insulators are miniral oils synthetic and other.

Solid insulators are paper cloth plastics porcelain.

. .

. miniral .

.

Resistance and Resistivity

Every material offers some resistance to the flow of an electric current through it. The resistance of a conductor on its material. It also depends on its material. It also depends on its temperature.

There are several factors that determine the electrical resistance of any wire.

1) the material which it is composed of.

2) the size of the wire

3) its temperature



<== | ==>
- -1-150 |
:


: 2018-11-11; !; : 246 |


:

:

, .
==> ...

818 - | 676 -


© 2015-2024 lektsii.org - -

: 0.013 .