Text 4. What is electricity?

Vocabulary

Electricity - электричество

Electrical equipment - электрооборудование

precision - точность

electrostatics - электростатика

electrification - электризация

friction - трение

electron theory of matter - электронная теория материи

charge - заряд

charged bodies - заряженные тела

directly proportional - прямо пропорциональный

inversely proportional - обратно пропорциональный

electric field - электрическое поле

lines of force - силовые линии

condense - r конденсатор

magnetic field - магнитное поле

magnetic lines of force - магнитные силовые линии

magnetic phenomena - магнитные явления

magnetic induction - магнитная индукция

residual magnetism - остаточный магнетизм

flow - поток

resistance - сопротивление

a column of mercury - столбик ртути

cross-section - поперечное сечение

cross-sectional area - площадь поперечного сечения

in series - последовательно

in parallel - параллельно

superconductivity - сверхпроводимость

lattice - решетка

1. Translate the text into Russian.

What is electricity? When the question is asked the answer is sometimes given that "no one knows". This is far from being correct. Science knows a great deal about electricity. It is possible to explain its behaviour under numerous and varied conditions, (l) to design electrical equipment like motors, generators, and transformers with great precision and efficiency, and to even say of what electricity is composed.

This statement is not to be misinterpreted to mean (2) that science knows everything about electricity. We still have much to learn.

A student usually starts to study electricity with electrostatics. First the theories of electrification by friction are given and the behaviour of an electroscope is explained. Then the properties of conductors and non­conductors of electricity according to the electron theory of matter are considered. Electrostatics deals (3) mainly with charges.

The first quantitative measurements of the force between charged bodies was made by Coulomb, a French scientist and engineer, in 1780. He proved experimentally (4) that the force acting between two charges is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them, or algebraically F=k(q1q2\d ) where F is the force, q1 and q₂ are the charges, and d is the distance between them. The constant k has a value which depends upon the units of charge chosen and upon whether the charges are in vacuum, in air, or in some other medium.

Then the important concept—the electric field is discussed. The electric field is defined as the forces in the space around a charged body.

The student should be able to make diagrams illustrating the electric field and the lines of force in the neighbourhood of charged bodies, define capacity, name the essential elements of an electrical condenser, and its general purpose.

In the space surrounding every magnet there exists a magnetic field. Although this field cannot be seen, it can be demonstrated and mapped out (5) or in other words the magnetic lines of force can be drawn, each line starting at some point near the North pole and ending at a corresponding point near the South pole.

These magnetic lines of force do not really exist; but they are useful for describing the different magnetic phenomena.

ПРИМЕЧАНИЯ:

(1) under numerous and varied conditions – в самых разнообразных условиях

(2) This statement is not to be misinterpreted to mean - было бы неправильным толковать это положение в том смысле

(3) deals - зд. рассматривает

(4) proved experimentally -доказал экспериментальным путем

(5) mapped оut -зд. Нарисовано