II. Translate the following sentences into Russian, call tense and voice .

1. The students were invited to the conference organized by the Academy.

2. Children are taught foreign languages at school.

3. They were shown the laboratories and the library of the University.

4. I am sure he will be listened to with great attention.

5. Lectures are always followed by practical work.

6. Electric motors will be spoken about in the next article.

7. He was sent for, as he was the only to help us.

8. Many new houses are being built in our country now.

9. This book was much spoken about at the last conference.

Lesson 3.

Text.

Electricity in Cells

A molecule consists of atoms. Each atom has electric charges called electrons, which move around in the atom. A simple cell may be made by putting a plate of copper and a plate of zinc in a glass of water and adding ten percent solution of sulphuric acid. The chemical action takes place on the zinc plate faster than it does on the copper plate, releasing electrons. Electrons in motion produce a current. Thus a direct current may be obtained by attaching terminals to the wires. We get an electric current because of motion of electrons. If the wires are connected to a galvanometer (an instrument for measuring a small movement of current) a small current flow will be shown on this instrument.

So, a cell consists of an electrolyte and two electrodes. Every cell has a positive terminal and a negative one. These terminals are used to connect the battery to the circuit. Since a battery is formed by connecting several cells, it is important to know how these cells should be connected to obtain the desired voltage for a circuit. There are two common ways of connecting cells either in parallel or in series. When cells are connected in series the positive terminal of the first cell is connected to the negative of the second cell. the positive terminal of the second cell - to the negative terminal of the third... and so on.

When cells are connected in parallel their negative terminals are connected together and their positive terminals are also connected.

Parallel wiring of several cells then gives only approximately the same force or voltage as one cell; but it produces approximately the combined amperage of all the cells (see Fig. 3).

In order to increase the voltage output cells should be connected in series. Series wiring is illustrated in Fig. 4.

 

Words and word combinations:

copper – медь

percent (%) – процент

sulphuric acid– серная кислота

releasing electrons – испускающий электроны

chemical action –химическая реакция

in series – последовательно

in parallel – параллельно

solution - 1)раствор, 2) решение

approximately – приблизительно

to take place – иметь место, происходить

Assignment:

I. Find the following words and word combinations in the text:

Состоять из, электроны в движении, приблизительно, инструмент для измерения,соединяются параллельно (последовательно), цинковая (медная) пластина, два распределенных способа соединения, электрическая цепь, важно знать, испускающий электроны, получит желаемое напряжение, 10 % раствор серной кислоты.

 

II. Give three forms of the verbs and translate them.

to produce, to connect, to put, to use, to add, to get, to take, to make, to form, to obtain. 

III. Answer the questions.

1. What does a molecule consist of?

2. How may a simple cell be made?

3. How is an electric current produced in a simple cell?

4. What is a cell used for?

5. What does a cell consist of

6. What is the function of the terminal?

7. What instrument is used for measuring a small movement of current?

8. In what way are cells connected in order to increase the amperage?

9. In what way are cells connected in order to increase the voltage output?

10. In what way are the terminals of series cells connected?