Exercise 1. Translate the words in brackets into English

Diodes

The diode design is simple. It has a cathode with a heater and a plate. When the filament voltage is turned on, the cathode emits electrons. Nega- tive voltage on the cathode repels the

electrons. Positive voltage on the plate at- tracts the electrons. Then the electrons re- turn through the external circuit to the cathode. The electric field is established within the tube. The current flows through the tube. This flow of electrons is known as the plate current. If negative voltage is applied to the plate, the current does not flow. The plate current flows only during the time when the plate is positive. Thus, the diode conducts the current in one di- rection only.

Diodes are used as rectifiers of alternating voltages, as detectors of radio signals, as switching devices, etc. So the only function of a diode is to convert alternating current voltage into direct current voltage.

Triodes

In a triode there are three electrodes: a cathode, a plate and a grid.

When heated the cathode emits electrons. The electrons flow from the cathode to the plate. The grid is placed between the cathode and the plate. It controls the flow of electrons. The closer the grid is to the cathode, the more influ- ence it has on the electron flow. Even if small negative voltage is applied to the grid, a large plate current flows. If large negative voltage is applied to the grid, the plate current decreases.

Due to this property of a triode, it can be used for amplification.

Exercise 1. Translate the words in brackets into English

1. (Работа электронных ламп) is based on the thermionic emission.

2. The electrode which (излучает) electrons is called a cathode.

3. The electrode which acts as (собиратель электронов) is called a

plate.

4. An electron tube is an evacuated or gas-filled envelope (содер-

жащий электроды).

5. The diode (устройство) is simple.

6. The cathode is used as an (излучатель) of the electrons.

7. The diode (проводит) current in one direction only.

8. All the triodes have the following electrodes: a cathode, a plate and the third element called (сетка).