My speciality. Овчинникова Т.Е - 23 стр.

       2.7.4 Read the question to each paragraph, answer it

1. What is a transistor? 2. In what case have we a filamentary transistor? 3. How
does the unipolar transistor operate?

      2.7.5 Identify the functions of the words with suffixes -еd and –ing
(paragraph 1). Find the sentence with the pronoun one and identify its function,
a conditional sentence and identify its type


        THE PHYSICAL MECHANISM OF CRYSTAL AMPLIFIERS
                        (TRANSISTORS)

1. The transistor is a device for the amplification of electrical signals; so it may not be
too far-fetched to refer in the discussion of its mechanism to the oldest and simplest
device of this type, namely, the electromagnetic telegraph relay. A weak current
arriving over a long transmission line actuates a switch which starts or blocks the
strong current from a local source. The essential part of this process can be described
as a signal which varies the conductivity in a current path of a local current source,
effected in this particular case by a variation of the cross section at a certain point.
2. As an alternative of such a modification of the geometric dimensions of the current
path, one could also consider a change of the specific conductivity, for instance, by va-
rying the number of carriers. This actually happens in a number of transistor types,
namely, by more or less intensive injection of additional charge carriers. Within the range
of this common mechanism, the various types differ only in the nature of the affected
current path. If the injection occurs into an ohmic conductor, we have the filamentary
transistor. If the affected current path is a p-n-junction, we have the n-p-n transistor.
Finally, in the point-contact transistor, the boundary layer of a metallic point
contact is affected by injected carriers. The last transistor type to be discussed, namely,
the unipolar transistor, operates like the relay by means of continuously variable
geometrical dimensions of the current path. This can again be interpreted as a variation of
the carrier concentration as in the other transistor types. In contrast to the other types, it
is here restricted to more or less extended boundary regions of the current cross section.
Furthermore, this variation applies to the majority carriers and not the minority
carriers.

        Notes to the text

The transistor is a device for the amplification of electrical signals, so it may not be
too far-fetched to refer in the discussion of its mechanism to the oldest and simplest
device of this type, namely, the electromagnetic telegraph relay. — Транзистор
является прибором для усиления электрических сигналов; при рассмотрении его
механизма можно сослаться на старейший и простейший прибор этого типа, а
именно электромагнитное телеграфное реле.