4. Answer the following questions:

1. What is Benjamin Franklin famous for?

2. When was he born?

3. How did he spend his childhood?

4. What discoveries did he make in electricity?

5. What physical terms did he invent?

6. What fields of science was he interested in?

7. What were his political views?

8. What was his contribution as a diplomat?

5. Put the verbs given in brackets in the proper Indefinite Tense (Present, Past, Future)

Model: Benjamin Franklin (to be) journalist and inven­tor, scientist and statesman, poli­tician and writer. - Benjamin Franklin was journalist and inven­tor, scientist and statesman, poli­tician and writer.

1. Benjamin Franklin (to live) a long life.

2. Benjamin (to like) to make things with his own hands, he (to make) a lot of experiments and (to invent) an open stove, which (to give) more heat and (to waste) less fuel than, a fireplace.

3. The lightning rod (to be) Franklin's greatest discovery and this invention and his studies of electricity (to bright) Franklin universal fame.

4. Franklin (to study) heat conductors, the origin of storms, med­icine, natural history, political economy and mathematics and he (to speak) several languages.

5. Franklin (to work) much for the cause of independence and (to help) Jefferson in writing the Declaration of Independence.

6. Put the verbs given in brackets in the proper Continuous Tense (Present, Past, Future)

Model: They (to work) in the laboratory from 8 till 12 today. – They will be working in the laboratory from 8 till 12 today.

1. Our factories (to produce) all kinds of machines and equipment nowadays.

2. At this time tomorrow the scientists (to discuss) important problems of the experiment.

3. Considerable changes (take place) currently in the organization of research in our University.

4. Our knowledge of environment (to increase).

5. He (repair) this equipment the whole day yesterday.

7. Put the verbs given in brackets in the proper Perfect Tense (Present, Past, Future)

Model: Our teacher (to give) the example of this rule. – Our teacher has given the example of this rule.

1. He (to do) this work by 7 o’clock tomorrow.

1. Our students (to answer) all the questions.

2. This problem (to consider) by our scientists by the end of the last century.

3. All the necessary equipment (to send) to the expedition.

4. The scientists in the sphere of national economy (to solve) many important problems recently.

8. Put the verbs given in brackets in Perfect Continuous Tense (Present, Past, Future)

Model: He (to carry out) the experiment since May. – He has been carrying out the experiment since May.

1. The scientists (to observe) Mars for a long time.

2. Chemists (to study) the atmosphere for about two thousand years before its composition was discovered.

3. By the first of November this teacher (to work) at our University for 20 years.

4. Our students (to study) French for five years by the next winter.

5. They (to read) the newspaper for two hours.

9. Speak about life and scientific work of Benjamin Franklin unit21 (revision). Lighting and invention of electric lamp

1. Translate the following text:

The cave-men could not light up their caves by pushing a button or lighting a lamp with a match. The only light they had at night was moonlight or the light of a bonfire.

Now we can turn night into day both indoors and outdoors. Torches, candles, oil lamps and gas lamps all seem old-fashioned to us now. Electric lamps have crowded them all out.

There are several different kinds of electric lamps — arc, incandescent, mercury vapour, neon (fluorescent) and others besides. They are all different in one important way from the kinds of lamps that were used before them: in an electric lamp nothing is on fire.

A Russian inventor, Paul Yablochkov, invented the arc lamp in 1876. In 1878 these lamps appeared in the streets of Paris. In arc lamps electricity produces light by jumping from the end of one carbon rod to the end of another. Compared with the former existing gas lamps they were so brilliant that many European cities began to use them.

Lamps using glowing wires were made as early as 1845, but they did not work well because all known filaments burned or melted before they got incandescent. It was Edison who produced a carbon-filament lamp which could operate at a temperature of about 1900 ^CC. Today, instead of carbon, we use tungsten. A tungsten filament usually operates at 2800°C.

In neon and mercury vapour lamps the current makes a gas glow. The glowing gas makes a chemical coating on the inside of the tube give off light.

Arc lamps and electric lamps with filaments that; get incandescent give off heat, too. Fluorescent lamps give off little heat.

The story of lamps and lighting has not ended. Scientists are trying to find even better ways of changing night into day.