7. Translate the following sentences:

1. Электрический мотор, преобразующий электрическую энергию в механическую, используется в повседневной жизни. 2. Говоря об электрическом токе, мы можем упомя­нуть имя Вольта. 3. Электрический пирометр измеряет температуру расплавленных металлов. 4. Поработав на фаб­рике, мой товарищ поступил в институт. 5. Электрические приборы, упомянутые в этой статье, были созданы русскими учеными. 6. Измеряя температуру горячих металлов, сту­дент пользовался пирометром. 7. Измерив температуру ме­талла, мы начали измерять температуру воды.

8. Put all possible questions to the following sentence:

The electric motor finds a wide application in industry.

9. Form sentences using the following expressions:

To play a part in; to go on foot; to do without; to make use of; to be familiar with; to get up; to go to bed; to watch television; owing to

10. Speak on:

1. The use of the electric current in industry.

2. The use of the electric current in our everyday life.

11. What do you call a device which:

1. measures the temperature of hot melted metals.

2. transforms electric energy into mechanical energy.

3. lifts objects weighing thousands of tons.

4. lights your room.

12. Enumerate your home appliances using electric energy

13. Put six general questions to the text.

14. Make an outline of the text.

15. Retell the text.

LESSON TWO

ENERGY

Scientifically speaking, energy is the ability to do work. There are various forms of energy, such as: heat, mechanical, electrical, chemical, atomic and so on. One might also mention the two kinds of mechanical energy—potential and kinetic, potential energy being energy of position while kinetic energy is energy of motion. It is well known that one form of energy can be changed into another.

Take a waterfall as an example. Water falling from its raised position, energy changes from potential to kinetic. If there is a hydroelectric plant at the waterfall, the energy of the falling water is used to drive the turbines. The tur­bines, driven by the kinetic energy of the running water, turn electric generators, these generators producing electric energy! Thus, the mechanic energy of falling water is turned into electric energy. The electric energy, in its turn, may be transformed into any other necessary form.

When an object loses its potential energy, that energy is turned into kinetic energy. Thus, in the above-mentioned example when water is falling from its raised position, it certainly loses its potential energy, that energy changing into kinetic energy (Fig. 1).

We have already seen that energy of some kind must _be_ employed to generate the electric current. The sources of energy usually employed to produce current are either chemi­cal, as in the battery, or mechanical, as in the electromagnetic generator. Chemical sources of current having a limited ap­plication, the great quantities of electric energy generated today come from various forms of mechanical energy.

Needless to say that rising standards of modern civili­zation and growing industrial applications result in an in­creasing need of energy. Every year we need more and more electric energy for the useful things that are done only owing

to electricity. However, the energy sources of the world are decreasing at the same time as the energy needs of the world are increasing. These needs will continue to grow as more motors and melted metals are used in industry and more electric current is employed in our everyday life. As a result, it is necessary to find new sources of energy.

Fig. 1. Examples of kinetic energy.

The,Sun is an unlimited source of energy. However, at present, only a little part of solar energy is being used di­rectly. How can we employ solar energy directly to produce useful energy? This is a question which has interested scien­tists and inventors for a long time. Lavoisier and other great scientists of the past melted metals with the help of solar furnaces. Today, solar furnaces illustrate just one of the numerous ways to harness the sun. Using semiconductors, scientists, for example, have transformed solar energy into electric energy.

Exercises