My speciality. Овчинникова Т.Е - 37 стр.

1. Let us consider some cases of electron tube's use. Tubes are common elements of
radio and electron devices. They are used as: rectifiers to rectify alternating current
into direct current; oscillators to produce oscillating waves; amplifiers to amplify the
input current and in many other functions.
2. At first let us consider tubes used as rectifiers, for example a half-wave rectifier.
Alternating current is rectified into direct current by means of a rectifier. A half-
wave rectifier consists of a diode in series with a resistance. To put a rectifier into
operation a source of alternating current should be applied to it. When a is
applied, the diode conducts. The rectifier passes current during positive half-
cycles of the applied voltage. Therefore, it is called a half- wave rectifier. Current
passes in one direction- it is direct current. Besides, it is a pulsating
current. Pulsations should be eliminated. They are eliminated by means
of a filter.

      2.12.6 Translate the word-combinations

electron tube, oscillating wave, half- wave rectifier, half cycle, applied voltage,
pulsating current, by means of.

      2.12.7 Answer the questions

1.How are t h e electron tubes used? 2. What do rectifiers do? 3. What k i n d of a
device produces oscillating waves? 4. What device rectifies alternating current
into direct cur-rent? 5. What should be done to put a rectifiers into operation? 6.
What is eliminated by means of a filter?

      2.12.8 Form verbs from these nouns, translate them

amplifier, rectifier, conductor,      elimination,   consideration, direction, pulsation,
oscillation, resistance, production

      2.13 Part 13

      2.13.1 Remember pronunciation of the following words

radar, target, coherent,     coherence, unique, ambiguity, magnetron, microwave,
susceptible.


      2.13.2 Read the words, pay attention to stress shift

production — productivity; volume — volumetric; simple — simplicity; operate —
operational; transmit — transmission; able — ability;   magnet — magnetic;
amplify — amplification; mature — maturity; necessary — necessity; complex —
complexity.