1. When was the voltaic cell invented?

2. What did the invention of the voltaic cell give?

3. What did Oersted decide to establish?

4. What did he find out?

5. When did the needle deflect?

6. Who repeated Oersted's experiment?

7. Do you know Ampere's rule?

8. What did Ampere establish and prove?

Exercise 1.2. Find the following equivalents in the text:

1. гальванический элемент

2. источник постоянного тока

3. зависимость между потоком тока

и намагниченной иглой

4. стрелка отклоняется

5. находится около проволоки

6. через которую проходит ток

7. проволока параллельна игле

8. ток возник

9. под прямым углом

10. помещена под иглой

11. отклонение стрелки

12. ценные наблюдения

13. под влиянием

14. благодаря которому

15. магнитное действие

16. без магнитов посредством электричества

17. действие тока в прямом проводнике

Exercise 1.3. Choose the right answer:

1. The invention of the voltic cell gave electrical experiments of …

a) alternating current. b) constant current.

2. Oersted decided to establish the relation between 

a) a flow of current and a magnetic needle 

b) a flow of current and a conductor

c) a magnet and a magnetic needle

3. A compass needle is deflected when brought near wire through which …

a) the current was reserved. b) the current flows.

4. The north end of the needle moves away when the current flows …

a) from left to right.

b) from right to left.

c) towards the conductor.

5. Magnetic effect can be produced without any ...

a) needles. b) magnets.

6. Ampere studied...

a) the deflection of the needle.

b) the behaviour of the current in a single straight conductor.

7. When a wire conducting a current is formed into a coil of several turns, the

amount of magnetism ...

a) is greatly decreased. b) is greatly increased.

8. The iron core acts as a magnet...

a) when the current passes along the winding.

b) while the current is flowing within the winding.

c) we double the current.

Exercise 1.4. Translate into English :

1 Датский ученый установил зависимость между потоком тока и намагниченной иглой.

2 Он обнаружил, что стрелка отклоняется около проволоки, через которую проходит электрический ток.

3 Стрелка отклонилась к проводнику под прямым углом.

4 Направление тока изменилось.

5 Когда возник ток, стрелка отклонилась.

6 Ток течет слева направо.

7 Когда проволока находится ниже стрелки, направление стрелки меняется.

8. Магнитное действие возникает под воздействием электричества.

9. Магнетизм тока усиливается в катушке.

Exercise 1.5. Translate the 3th, the 4^th paragraphes

Вариант 10

Read the text:

CONDUCTORS AND INSULATORS

1. All substances have some ability of conducting the electric current, however, they differ greatly in the ease with which the current can pass through them. Metals, for example, conduct electricity with ease while rubber does not allow it to flow freely. Thus, we have conductors and insulators. What do the terms "conductors" and "insulators" mean? Substances through which electricity is easily transmitted are called conductors. Any material that strongly resists the electric current flow is known as an insulator.

2. Let us first turn our attention to conductivity that is the conductor's ability of passing electric charges. The four factors, conductivity depends on, are: the size of the wire used, its length and temperature as well as the kind of material to be employed. It is not difficult to understand that a large water pipe can pass more water than a small one. In the same manner, a large conductor will carry the current more readily than a thinner one. It is quite understandable, too, that to flow through a short conductor is certainly easier for the current than through a long one in spite of their being made of similar material. Hence, the longer the wire, the greater is its opposition, that is resistance, to the passage of current. As mentioned above, there is a great difference in the conducting ability of various substances.

3. For example, almost all metals are good electric current conductors. Nevertheless, copper carries the current more freely than iron; and silver, in its turn, is a better conductor than copper. Generally speaking, copper is the most widely used conductor. That is why the electrically operated devices in your home are connected to the wall socket by copper wires. Indeed, if you are reading this book by an electric lamp light and somebody pulls me metal wire out of the socket, the light will go out at once .The electricity has not been turned off but it has no path to travel from the socket to your electric lamp. The flowing electrons cannot travel through space and get into an electrically operated device when the circuit is broken. If we use a piece of string instead of metal wire, we shall also find that current stops flowing.

4. A material like string which resists the flow of the electric current is called insulator. There are many kinds of insulation used to cover the wires. The kind used depends upon the purposes the wire or a cord is meant for. The insulating materials we generally use to cover the wires are rubber, asbestos, glass, plastics and others. Rubber covered with cotton, or rubber alone is the insulating material usually used to cover desk lamp cords and radio cords. Glass is the insulator to be often seen on the poles that carry the telephone wires in city streets. Glass insulator strings are usually suspended from the towers of high voltage transmission lines. One of the most important insulators of all, however, is air. That is why power transmission line wires are bare wires depending on air to keep the current from leaking off. Conducting materials are by no means the only materials to play an important part in electrical engineering. There must certainly be a conductor that is a path, along which electricity is to travel and there must be insulators keeping it from leaking on the conductor.