IV. Translate the following sentences and define the func­tions of tfie word that

1. It is clear that the greater the number of free elec­trons in a substance, the better that substance conducts the electric current. 2. An electric current passing through a wire heats that wire. 3. It is the unit of current that is named after Ampere. 4. That a solenoid has two poles that attract and repel the poles of other magnets is a well-known fact. 5. The physics of bodies at rest is much simpler than that of the bodies that are in motion. 6. There was a time when light­ning was a problem that scientists tried to solve but at present everybody knows that it is an electric spark like that pro­duced by the electric machines.

V. Translate the following sentences paying attention to the words in bold type:

1. Rubber is a very poor conductor of electricity. 2. This is the very appliance which I need for my experiment. 3. Lo­monosov was born in the family of a poor peasant. 4. All metals are poor insulators of electric current. 5. The Soviet Union is a great country, 6. Next summer I shall have a rest in the country, 7. The rest of the story should be translated at home. 8. Electricity at rest or in a static condition does no work. 9. Heat causes many chemical reactions. 10. What causes the electrons to flow along the wire? 11. A short cir­cuit may be the cause of fire.

VI. Fill in the blanks with suitable prepositions and form sentences with the following infinitives: -

to equip to depend to compare to consist to contribute to be interested to be familiar to point to look ...

VII. Compare:

1. Potential energy and kinetic energy.

2. A series circuit and a parallel circuit.

3. A conductor and an insulator.

4. The magnetic effect of an electric^jcurrent and the heating effect of an electric current.

VIII. Translate the following sentences, paying atten- tion to the words in bold type:

1. Ampere's contribution to "electrodynamics" as he called the new science began in 1820. 2. As it is impossible to detect electricity by our physical senses, we generally detect it by its effects. 3. An electromagnet loses its magnetic prop­erties as soon as the current is turned off. 4. In certain branches of industry, chemical energy is not so widely used as mechanical energy. 5. The average speed of all molecules remains the same as long as the temperature is constant. 7. In order to produce electricity more economically the generators must be as large as possible. 8. As a gas is cooled, it loses heat as well as energy. 9. The magnetic effect of an electric current is the subject of the present article, as for the heating effect it was dealt with before.

IX. Form nouns from the following verbs and translate them:

to invent, to connect, to discover, to achieve, to ob­serve, to state, to contribute, to conduct, to produce, to op­erate, to deflect

X. Give a short summary of the text.

XI. Look at Fig. 9 and describe Oersted's discovery.