1. Discussing about mass media

1. Talk about your favorite mass media

1. Literature: English File by Clive Oxenden Intermediate Oxford University Press.

Additional Literature: R. Murphy “Essential Grammar in Use” Cambridge University Press

Lesson-34

Text: ELECTRON TUBES

Let us consider electron tubes. Electron tubes in use nowadays are a diode, a triode, a tetrode and a pentode. The main parts of electron tubes are electrodes. Electrodes are placed into a glass or metal bulb.

A diode contains the cathode and the plate. When a diode operates the cathode emits electrons, the plate collects.

A triode contains the cathode, the plate and the control grid. When the tube operates the cathode emits electrons, the plate collects them and the grid controls the flow of electrons. There-fore, the grid is called a control grid.

A tetrode contains the cathode, the plate, the control grid and the screen grid.

When a tube operates it may oscillate. The function of the screen grid is to eliminate oscillations. There-fore it is called a screen grid.

A pentode contains two electrodes and three grids: the control grid, the screen grid and the suppressor grid. When a pentode operates the suppressor grid eliminates the secondary emission.

Common troubles in tubes are an open heater and low emission. These troubles result from constant use or from some other reason. In case a tube has a trouble it stops operating or operates badly. A tube with a trouble should be replaced by another one.

EXERCISES

A

Find the correct variant. Remember it:

1. A pentode contains

a) the cathode, the plate, two screen grids and the suppressor grid

b) the cathode, the plate, the control grids, the screen grid and the suppressor grid

1. Tetrode contains

c) the cathode, the plate, the suppressor grid and the screen grid

d) the cathode, the plate, the suppressor grid and control grid

Answer the questions:

1.What electron tubes are in use?

2.What are the main parts of electron tubes?

3.What does a diode contain?

4. What does a triode contain

5.What does a tetrode contain?

6. What electrodes contain a pentode?

7.What common troubles in tubes?

Test

.1. The main parts of electron tubes are_________

a}batteries b}electrodes c}wires d}plates

2_____ contains the cathode and the plate.

a}a pentode b}tetrode c}triode d}diode

3. _____ contains the cathode, the plate and the control grid.

a}a pentode b}tetrode c}triode d}diode

4._____contains the cathode, the plate, the control grid and the screen grid.

a}a pentode b}tetrode c}triode d}diode

5. _______ contains two electrodes and three grids: the control grid, the screen grid and the suppressor grid.

a}a pentode b}tetrode c}triode d}diode

Glossary

English	Russian	Kazakh
Tubes	лампы	жарықшам
to contain	вместить	орналастыру
grid	решётка	тор
emits	испускать	жіберу
suppress	подавлять	қысу

SIW

Find and learn 10-12 words, write examples

SIWT

Retelling the text

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

2.Raymond Murphy”Essential Grammar in Use”

Lesson-35