1.Content

1.1 Grammar. Present Perfec

1. Write sentence or questions with the present perfect.

He|ever|be there? Has he ever been there?

1. You/ever buy/clothes from that shop?

1. I/not read/ the newspaper today.

1. We/never be/ to the new shopping centre.

1. You brother/ live abroad/ all this life?

1. They/ go/ to live in South America.

1. She / never fly/ before.

1. He / not meet / his ф

1.Translate into Russian. Mind provided that.

1. A circuit operates well provided that it does not have any trouble.

2. The bulb lights provided that the circuit is connected to the cell.

3. A cell supplies energy provided that its electrodes are of different materials.

Text :Capacitors

A capacitor is one of the main elements of a circuit. It is used to store electric energy. A capacitor stores electric energy provided that a voltage source is applied to it.

The main parts of capacitor are metal plates and insulators. The function of insulators is to isolate the metal plates and in this way to prevent a short.

In the diagram one can see two common types of capacitors in use nowadays: a fixed capacitor and variable one. The plates of a fixed capacitor cannot be moved; for this reason its capacity does not change. The plates of variable capacitor move; its capacity changes. The greater the distance between the plates, the less is the capacity of a capacitor. Variable capacitors are commonly used by radiomen; their function is to vary the frequency in the circuit. Fixed capacitors are used in telephone and radio work.

Fixed capacitors have insulators produced of paper, ceramics and other materials; variable capacitors have air insulators. Paper capacitors are commonly used in radio and electronics; their advantage is their high capacity: it may be higher than 1,000 picofarad.

Besides, electrolyte capacitors are highly in use. They also have a very high capacity: it varies from 0.5 to 2,000 microfarad. Their disadvantage is that they change their capacity when the temperature changes. They can operate without a change only at temperatures not lower than −40°C.

Common troubles in capacitors are an open and a short. A capacitor stops operating and does not store energy in case it has a trouble. A capacitor with a trouble should be substituted by a new one.

Answer the questions

1.What element is a capacitor?

2.What does a capacitor store?

3.What are the main parts of capacitor?

4.What types of capacitors can we see in the diagram?

5.Were are fixed capacitors used?

6.What do fixed capacitors produce?

2.Complete these sentences using the correct variant:

1. A capacitor is used a) to supply voltage

b) to increase the voltage output

c) to store energy

2. The main parts of capacitor are a) insulators only

b) metal plates only

c) metal plates and insulators between them

3. The function of insulators is a) to store energy

b) to isolate the metal plates

c) to prevent a short between the metal plates

4. The capacity of capacitor a) the size of the plates

depends on b) the distance between the plates

c) the material of the insulators

5. The capacity of a fixed capacitor a) is constant

b) is varied

6. The plates of a variable capacitor a) can be moved

b) cannot be moved

7. In order to charge a capacitor a) to the metal plates

voltage source is applied b) to the insulator

8. The greater the distance a) the greater is the capacity

between the plates of a capacitor

b) the less is the capacity

Glossary

English	Russian	Kazakh
A capacitor	кондинсатор	кондинсатор
insulator	изолятор	оқшау
circuit	обмотка	оралым
vary	разнобразить	түрлендіру
source	источник	көзі
to apply	применять	қолдану
to isolate	изолировать	оқшаулау

SIW:Speak about another parts of capacitors

SIWT:Retell the text

Literature: 1.Orlovskaya I.V.”English”-Moscow-2007

2.Raymond Murphy”Essential Grammar in Use”

3.John Eastwood”Oxford practice grammar”

Lesson-10, 11

Radio waves in the ionosphere

When a radio wave leaves a transmitting antenna, it travels in all directions. Part of the signal travels along the ground and is called the ground wave. Part of the signal travel through the lower atmosphere in a directing parallel to the ground. Another part travels at an angle to the ground. The part travelling through the lower atmosphere is called the tropospheric wave; the part travelling at an angle to the ground – the ionospheric wave.

In the high – frequency part of the radio spectrum (3-30mc.) the ground and tropospheric wave components travels short distances, not more than 25 or 30miles. The ionospheric wave component of the signal can travel to great distances, making long – distance short – wave communication possible.

As the ionospheric wave leaves the transmitting antenna, it starts traveling and reaches a region called the ionosphere.

This region begins at a height of about 60miles above the ground. On reaching the ionosphere, radio waves supply the free electrons of the region with electromagnetic energy. As result, the free electrons start vibrating and radiate this energy the way the electrons in a transmitting antenna radiate energy.

Exercises

Find the correct variаnt. Remember it:

1.when a wave leaves an antenna

a) it travels in one direction

b) it travels in all directions

2.the part traveling along the ground

a) is called the tropospheric wave

b) is called the ground wave

3.the part traveling at an angle to the ground

a) is called the ground wave

b) is called the ionosheric wave

4.ionospheric waves travel

a) long distances

b) short distances

5.long-distance short wave communication is possible

a) due to ground waves

b) doe to tropospheric waves

c) doe to ionospheric wavs

6.a region called the ionosphere is reached

a) by tropospheric waves

b) by ionospheric waves

Finish the sentences using the words with the opposite meaning:

1. part of a wave travels at an angle to the ground … … .

2. the part traveling through the lover atmosphere is called the troposphere wave … … .

3. ground waves can travel short distances… … .

4. lonospheric waves make long-distance short wave communication possible… … .

5. lonospheric waves reach the ionospheric region… … .

C

Answer the following questions:

1.In what direction do waves leaving an antenna travel? 2. What is the part of the signal traveling along the ground called? 3. What is the part of the signal traveling at an angle to the ground called ? 4. What is the part of the signal traveling through the lower atmosphere called? 5. What distances does the ground wave component travel? 6. What distances does the ionospheric wave component travel? 7. What waves make long-distance short-wave communication possible? 8. What region do ionospheric waves reach? 9. At what height does a region called ionospheric begin? 10. What is the difference between ionospheric waves and ground waves?

Glosarry

English	Russian	Kazakh
leave	покинуть	қалдыру
angle	угол	бұрыш
Long-distance	длинно-дистанционный	ұзақ қашықтық
measurement	измерение	өлшем
region	местный	аймақтық
height	высота	биіктік
sphere	сфера	аймақ
possible	возможно	мүмкін

SIW:

Name 10-15 words and phrases, give examples

SIWT: Retell the text

Literature: 1.Orlovskaya I.V.”English”-Moskow-2007

2.Raymond Murphy”Essential Grammar in Use”

3.John Eastwood”Oxford practice grammar

Text: Electric Cells

An electric cell is used to product and supply electric energy. It consists of an electrolyte and two electrodes. Electrodes are used as terminals, they connect the cell to the circuit – current passes through the terminals and the bulb lights.

Cells can be connected in series, in parallel and in series – parallel. In order to increase the current capacity cells should be connected in series. In case buttery has a large current capacity and a large voltage output, its cells are connected in series – parallel.

When cells are connected in series the positive terminal of one cell is connected to the negative terminal 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.

In case a cell has a trouble it shops operating badly. This cell should be substituted by another one.

Bulb [ bлlb ] электрическая лампа

to light [lait] зажигать, обжигать

to increase [ in’kri:s ] увеличивать(ся), возрастать

to substitute заменять

and so on и так далее