- •1. Learn the following active words and use them in the sentences of your own
- •3. Look through the text and write out the English equivalents of the following words and word combinations. Use them in the sentences of your own.
- •5. Give short answers to the following questions:
- •7. Translate the following sentences:
- •1. Learn the following active words and use them in the sentences of your own.
- •2. Translate the following chains of words. Define what parts of speech they are
- •3. Look through the text and find the English equivalents to the following words and word combinations; use tem in the sentences of your own.
- •4. Translate the following sentences paying attention to the participle:
- •1. Learn the following active words and expressions. Use them in the sentences of your own.
- •4. Answer the following questions:
- •5. Work in pairs. Put questions to your partner and he (she) will answer them.
- •8. Translate the following sentences paying attention to the words need and turn:
- •9. Put all possible questions to the following sentences:
- •10. Define the following words according to the model given below.
- •13. Describe Fig. 2.
- •Exercises
- •Learn the following active words and use them in the sentences of your own:
- •2. Translate the following sentences, paying attention to the gerund:
- •7. Translate the following sentences paying attention to the words in bold type:
- •8. Put 5 questions to the text beginning with what.
- •9. Speak on the story told by the early Scandinavians.
- •10. Make an outline of the text.
- •1. Learn the following active words and use them in the sentences of your own.
- •2. Look through the text and find the English equivalents of the following words and word combinations:
- •5. Find the gerund in the text, define its function.
- •8. Translate the following sentences paying attention to both, both...And:
- •9. Fill in the blanks with prepositions:
- •10. Translate into Russian:
- •11. Form five sentences combining suitable parts of the sentence given in Columns I and II:
- •12. Describe Franklin's kite experiment.
- •13. Give a short summary of the text.
- •Exercises
- •1. Learn the following active words and Expressions
- •Look through the text and find the English equivalents of the following words and word combinations:
- •8. 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):
- •11. Use the following expressions in sentences of your own:
- •13. Speak on magnetism.
- •15. Describe Figs 3 and 4.
- •Exercises
- •8. (A) For the names of the countries given in Column I find the names of the nations given in Column II:
- •10. Speak on:
- •11. Make an outline of the text.
- •12. Retell the text.
- •Exercises
- •1. Learn the following active words and use them in the sentences of your own:
- •2. Define the functions of the participle and the gerund in the text.
- •4. Answer the following questions:
- •5. Fill in the blanks with suitable words and word combinations given below:
- •6. (A) For the verbs in Column I find suitable nouns in Column II.
- •7. (A) Translate the following word combinations:
- •10. The following statements are not true to the fact. Correct them:
- •11. Make an outline of the text.
- •12. Retell the text.
- •1. Learn the following active words and use them in the sentences of your own:
- •2. Translate the following word chains into Russian, define what part of speech the words are.
- •4 Translate into Russian:
- •8. Form 10 sentences using the following words:
- •10. Translate the following sentences paying special attention to the words in bold type:
- •11. Retell the text.
- •12. (A) Fill in the blanks with prepositions, if necessary; (b) retell the text:
- •1. Learn Active Words and Expressions
- •2. Look through the text and find the English equivalents to the following words and word combinations. Use them in your own situations.
- •The Infinitive
- •2. Translate the following sentences paying attention to the infinitive
- •3. Translate the following sentences paying special attention to the words in bold type:
- •4. Translate the following sentences paying special attention to the infinitive:
- •5. Fill in the blanks with the words one or for:
- •6. Write out from the text all the sentences where the infinitive is used, and define its function. .
- •1. Active Words and Expressions
- •3. According to the models given below form sentences combining suitable parts of the sentence given in Columns I, II, III, IV,
- •5. Work in pairs, ask your fellow-students questions:
- •6. Explain why:
- •Exercises
- •Exercises
- •Exercises
- •Exercises
- •Exercises
- •Exercises
- •Exercises
- •1 Learn the following active words and expressions and use them in the sentences of your own.
- •3. (A) Find the non-finite forms of the verb in the text; (b) define their functions.
- •4. Translate the following words and define what parts of speech they are:
- •5. Write out the adjectives with the suffix -able from the text. Translate them.
- •7. Answer the following questions:
- •9. Translate the following word combinations and use them in sentences of your own:
- •Exercises
- •2. (A) Give headings to each paragraph of the text; (b) explain why you have given such headings.
- •3. Translate the following sentences:
- •4. Define the non-finite forms of the verb met in the text.
- •5. Put 10 questions to the text.
- •6. Translate the following sentences:
- •7. Speak on:
- •Exercises
5. Fill in the blanks with the words one or for:
1. Moscow is ... of the largest cities in the world. 2. ... must remember that it is necessary to study English at leas!
an hour a day. 3. As ... rubber it was brought to Europe as early as the 15th century. 4. ... understands the importance of electricity when ... sees trams, trolley-buses and trains driven by it. 5. The energy of the atom is used ... peaceful purposes in our country. 6. ... must know the chemical properties of the atom. 7. We produce rubber ... it is quite necessary ... the development of our industry. 8. In 1819 Volta returned to Como ... he wanted to spend the rest of his life there. 9. This is a more important problem than that ... .10. I haven't got a dictionary, I must have ... .
6. Write out from the text all the sentences where the infinitive is used, and define its function. .
7. Make up sentences according to the model using the verbs given below.
Model: We could not help speaking about the achievements of Russian physicists.
to answer, to repeat, to mention, to observe, to change, to think, to remember
8. Give antonyms for the following words:
north pole, dark, on the one hand, small, arrangement, larger, magnetized, unfamiliar, like, positive, similar, to rest, in motion
9. Answer the following questions:
1. What types of electricity do you know? 2. What is the difference between electricity at rest and electricity in motion? 3. What kind of experiments did Galvani carry on? 4. What did Franklin prove? 5. What are the two kinds of electrical charges? 6. Who was the first to produce a steady continuous current? 7. What was Volta? 8. What can you: say about the behavior of static charges? 9. What did Volta take interest in? 10. What did Volta's discovery result in? 11. What did the Volta device consist of? 12. Where did he spend the rest of his life?
10. Explain the meaning of the following compound words:
newspaper, schoolboy, thunderstorm, icebreaker, waterfall, fisherman
11. Retell Volta's biography.
LESSON ELEVEN
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.
Let us turn our attention, now, to the electric current itself. 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. What can we say about the electron? 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.
The reader is certain to remember that a negatively charged electron moves to the positive end of the wire. It had been supposed to move in the wrong way,from the positive end of the circuit to the negative, long before the electrons were discovered. In fact, when a wire is said to be carrying a current from left to right, the electrons in it are really flowing from right to left.
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 energy to be generated at present is a. c. We know it to find a wide application for lighting, heating, industrial and other purposes.
The student may be probably asking himself: "Why is d. с ever used?" 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. in practice.
Exercises