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9. Match the following words and phrases with their translation.

A. 1. contact loss; 2. loss of vacuum; 3. energy loss; 4. metal loss; 5. temperature loss

1. потеря энергии; 2. спад температуры; 3. угар металла; 4. потеря в контакте; 5. ухудшение вакуума

В. 1. impurity concentration; 2. ion concentration; 3. rate of discharge; 4. corrosion rate; 5. information rate

1. концентрация ионов; 2. скорость коррозии; 3. скорость передачи информации; 4. скорость разряда; 5. концентрация примесей.

10. Choose the nouns from the following words.

  1. a. producer; b. produced; c. production

  2. a. relativity; b. relative; c. relatively

  3. a. formed; b. formation; c. formally; d. formality

  4. a. employment; b. employed; c. unemployment; d. employer

  5. a. possible; b. impossible; c. possibility; d. impossibility

  6. a. continued; b. continuation; c. continuous

  7. a. conduct; b. conductor; c. conduction; d. conductivity

  8. a. consideration; b. considered; c. considerably

  9. a. attract; b. attraction; c. attractive; d. attracted

11. Match the following expressions with their translation:

a) intrinsic semiconductor

b) mobile electrons

c) ground connection

d) extrinsic semiconductor

e) discharge rate

f) recombination rate

g) flame resistance

1) скорость рекомбинации

2) примесный полупроводник

3) подвижные электроны

4) скорость разряда (аккумулятора)

5) полупроводник с собственной проводимостью ( беспримесный)

6) огнестойкость

7) заземление

12. Choose as many words from the table оf ex. 1 as you can and form sensible sentences in Past Simple Passive or Past Continuous Passive (affirmative, negative and interrogative).

For example:

  • Your heating bills could be greatly reduced by using low-energy heaters.

Specialist reading

13. Read the text “Electrons and Holes” only once. How much can you remember? Answer these questions without additional reading.

  1. What does take place in an atom when one electron frees itself from a covalent bond?

  2. Is the hole able to attract electrons?

  3. Can you define the process of recombination?

  4. Can you say anything about the rate of recombination?

  5. What is intrinsic semiconductor?

If you failed try to answer these questions again after doing the exercises given below the text.

If the temperature of a silicon crystal is above absolute zero, some of the valence electrons will receive sufficient energy to free themselves from covalent bonds.

When an electron leaves the covalent bond it leaves behind it an ‘absence of an electron’. This absence of an electron consists of a missing negative charge ‘e’, and it is equivalent to a positive charge called ‘a hole’.

Each hole is able to attract electrons and can be filled by a passing electron. This process is called recombination. Recombination causes a continual loss of holes and free electrons. The rate of recombination of holes and electrons is always equal to the rate of production of new holes and electrons. The total number of free electrons and holes is constant. The material having equal concentrations of mobile electrons and holes is called an intrinsic semiconductor.