Learn the following active words and Expressions

arrange(v)               организовать(ся)

bar (n)                    брусок

consist of                состоять из

carry out (v)            выполнять, осуществлять

minute (a)               мельчайший

obtain (v)                получать, добывать

point (v)                 указывать

possess(v)          обладать

physicist(n)        физик

pull away (v)                   оттягивать

reference(n)        ссылка

relation (n)              отношение

similar(a)                похожий

weight(n)                 вес                  

 

2. Translate the following word chains into Russian. Define what parts of speech the words are:

Order – disorder - disorderly; attract-attractive-attraction; relate – relative – relatively- relation – relationship; magnet – magnetic – magnetize – magnetization.

 

3. Look through the text and find the English equivalents of the following words and word combinations, use them in the sentences of your own:

Ссылаться на что-либо, с одной стороны, с другой стороны, проявить большой интерес к, в честь своего открывателя, обобщить, вместо, другими словами, не могли не повторять.

4. (a) Translate the following sentences; (b) define the non-finite forms of the verb:

1. Protecting buildings from lightning strokes was a great achievement in the field of electricity. 2. Speaking of the magnet, the inventor made reference to its property of attracting iron and steel. 3. Experiments showing the changes in substances are very important for industry. 4. Russian engineers constructed many hydroelectric stations, the one on the Angara being one of the largest. 5. The teacher minds our translating such an easy text with a dictionary. 6. In studying magnetism, we cannot help observing the relation between magnet ism and the electric current. 7. Having invented the lightning conductor, Franklin continued working on the problem о atmospheric electricity. 8. Having experimented with electricity and magnetism, Gilbert wrote a book on magnetism 9. Gilbert greatly contributed to the study of magnetism, Galileo taking great interest in Gilbert's achievements. 10. The atoms of different substances have different weights, their properties being also different.

5. Translate the following questions into English and answer them:

1. Существует ли связь между электричеством и магнетизмом? 2. Знаете ли вы, кто открыл магнетизм? 3. Что вы знаете об атмосферном электричестве? 4. Кто доказал, что наша Земля является большим магнитом? 5. Что вы знаете о магнетизме? 6. Каковы свойства магнита? 7. Кто создал первый телескоп в мире? 8. Какие опыты проводил Франклин?

6. Translate the following sentences paying attention to the word in bold type:

1. After the experiment had been carried out the student; carried the devices away. 2. These electrical devices are very large. Who can help me to carry them to another laboratory; 3. Why cannot you do without the thermometer? The temper­ature of this metal is known. 4. What were the students doing when the teacher came into the classroom? They were doing the exercises. 5. On heating, ice turns into water. 6. I see nothing, turn the light on, please. 7. Do not turn the light off, I shall go on working. 8. Turn the page and go on translating the text. 9. He could not go to the cinema yesterday.

7. Make up a story of Franklin's kite experiment using the following sentences and sentences of your own (our sentences are given in a disorderly way):

1. The key was connected to the lower end of the string, 2. The story about Franklin's famous kite is known all over the world. 3. They took some necessary things such as: a kite with a long string, a key and so on. 4. It was proved that lightning is a discharge of electricity. 5. It was a stormy day. 6. The electricity was conducted from the clouds down the string to the key. 7. The kite was flying high among the clouds. 8. The rain wetted the string. 9. Atmospheric electricity greatly interested Franklin. 10. The rain fell.

8. Define what parts of speech these words are:

application, ability, continuous, use, important, numer­ous, civilization, electric, familiar, reader, widely, useful, powerful, property, certainly

9. Form sentences with each of the following words:
similar, simple, single, magnetic, orderly, practical, scientific.

10. Use the following expressions in sentences of your own:

all over the world; as well as; in this connection; in the form of; needless to say; to pay attention to

11. Put two questions to each paragraph of the text and answer them.

Speak on magnetism.

13. Compare:

1. A generator and a motor.

2. Potential power and kinetic power.

3. Chemical power and mechanical power.

4. Nuclear power station and steam power station.

LESSON FIVE

 

ELECTRIC CURRENT

Ever since Volta first produced a source of steady contin­uous current, men of science have been forming theories on this subject. For some time they could see no real difference between the newly-discovered phenomenon and the former understanding of static charge. Then the famous French scien­tist, Ampere (after whom the unit of current was named) determined the difference between the current and the static charges. In addition to it, Ampere gave the current direc­tion: he supposed it to flow from the positive pole of the source round the circuit and back again to the negative pole. We know him to be right in his first statement but he was certainly wrong in the second, as to the direction of current. The flow of current is now known to be in a direction opposite to what he thought.

 The current which flows along wires consists of moving electrons. In other words, the flow of moving electrons is one form of the electric current.  We consider the electron to be a minute particle having an electric charge. We also know that charge to be negative. As these minute charges travel along a wire, that wire is said to carry an electric current.

In addition to travelling through solids, however, the electric current can flow through liquids, as well and even through gases. In both cases it produces some most important effects to meet industrial requirements. Some liquids, such as melted metals for example, conduct current without any change to themselves. Others, called electrolytes, are found to change greatly when the current passes through them.

When the electrons flow in one direction only, the current is said to be d. c, that is, direct current. The simplest source of power for direct currents is a battery, for a battery pushes the electrons in the same direction all the time (i. е., from the negatively charged terminal to the positively charged terminal).       

The letters a. c. stand for alternating current. The current under consideration is known to flow first in one direction and then in the opposite one. The a. c. used for power and lighting purposes is assumed to go through 50 cycles in one second (Fig. 6).

One of the great advantages of a. c. is the ease with which power at low voltage can be changed into an almost similar

amount of power at high voltage and vice versa. Hence, on the one hand alternating voltage is increased when it is necessary for long-distance transmission and, on the other hand, one can

decrease it to meet industrial requirements as well as to oper­ate various devices at home. In fact, at least 90 per cent of electric power to be generated at present is a. c. We know it to find a wide application for lighting, heating, industrial and other purposes.

In spite of the fact that almost all electrical power is usually generated and transmitted in the form of a. c, there are numerous cases when d. с is required. For this reason, it is quite possible to generate a. c. then transform it into d. с

We cannot help mentioning here that Yablochkov, our Russian scientist and inventor, was the first to apply a. c. inpractice.

Exercises

 

1. Learn the following active words and use them in the sentences of your own:

advantage (n)           преимущество

alternating current        переменный ток

decrease (v)                   понижать(ся), уменьшать(ся)

determine (v)            определять, устанавливать

direct current            постоянный ток

direction (n)                  направление

in­crease (v)                   повышать(ся), увеличивать(ся)

liquid (n)                       жидкость

particle (n)                    частица

pole (n)                     полюс

solid (n)                    твердое вещество

statement (n)                 утверждение

subject (n)                     предмет, тема

terminal (n)                   клемма

voltage (n)                     напряжение