Power Engineering. Соколова Е.В. - 26 стр.

      9 Lesson 9

      9.1 Прочтите слова согласно транскрипции

      thermionic , conveniently , migrate, within , coincide saturation , consequently
, maximum

      9.2 Прочтите слова, обращая внимание на смещение ударения

      active -activity; constitute -constitution; increase-increase; saturate –saturation

      9.3 Сгруппируйте эквиваленты

      magnitude, coincide, according to, contain, saturation, curve, replenish, attract

      согласно, кривая, содержать, притягивать, пополнять, совпадать, величи-
на, насыщение

      9.4 Сгруппируйте синонимы

      emit, arrive, vary , constitute, velocity, change, speed, come, set up, give off

      9.5 Прочтите и переведите текст

      Diodes

       1. Thermionic tubes are conveniently classified according to the number of ac-
tive elements. The simplest is the diode, which contains two active elements, a cath-
ode and a plate or anode.
       2. If the plate is made positive with respect to the cathode by connecting a bat-
tery or other source of potential between them, electrons emitted by the cathode will
be attracted to the plate; on arriving there they deliver their electrical charges to the
plate structure, then migrate as free electrons within the metal and through the battery
back to the cathode to replenish its supply. This continual flow of electrons consti-
tutes an electric current, passing through the plate circuit of the tube. The magnitude
of the current depends only upon the number of electrons per second arriving at the
plate, and this in turn is a function of cathode temperature and plate potential.
       3. The circuit of Fig. 1 may be used to investigate these relations. If the heater
current If is held constant at a value li, and the plate voltage Еъ is increased from
zero, the plate current , will vary in the manner shown by the lower curve in Fig. 2. If
now the heater current is increased to a new value Ifa thereby raising the cathode
temperature, the upper curve of Fig. 2 results. It will be noted that the two curves al-
most coincide at the smaller plate voltages, and then each becomes almost horizontal
in the upper region, but at different values of plate current. The levelling off of plate
current is known as temperature saturation: it is due to the fact that all the electrons
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