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17. Match the terms in Table a with their definitions in Table b.

Table A

Table B

  1. concentration

  2. absorption

  3. equipment

  4. impurity

  5. resistance

    1. A process in which something takes in liquid, gas, or heat.

    2. The ability of a substance to stop the flow of an electric current through it.

    3. The amount of a substance contained in a liquid.

    4. The tools, machines, clothes etc that you need to do a particular job or activity.

    5. A substance of a low quality that is contained in or mixed with something else, making it less pure.

Speaking

18. Summarize the text “Covalent Bonds” in 150 words.

19. In pairs ask and answer text-based questions.

For example:

  • How many elements are known to science today?

  • Do you know that some elements do not exist at all in nature?

  • How can we define valence electrons?

  • And what if we consider atoms in a solid piece of pure silicon?

20. Divide into 2 groups. Group 1 translates Extract a and group 2 – extract b of the text “Semiconductors” with a dictionary in writing.

Extract A

The two semiconductor materials used in the manufacture of semiconductor devices, such as diodes and transistors, are germanium and silicon. Both these materials fall into group IV of the Periodic Table of Elements. An atom of either substance may be represented by a central core having a positive charge and surrounded by orbiting electrons, each having a negative charge.

In its solid state silicon forms crystals of the diamond type, i.e. it forms a cubic lattice in which all the atoms except those at the surface are equidistant from their immediately neighbouring atoms. A study of crystal structure shows that the greatest number of atoms that can be neighbours to a particular atom at an equal distance away from that atom and yet be equidistant from one another is four. Hence each atom in a silicon crystal has four neighbouring atoms. In the crystal lattice each atom employs its four valence electrons to form covalent bonds with its four neighbouring atoms; each bond consists of two electrons, one from each atom. Each pair of electrons orbits around both its parent atom and a neighbouring atom.

Extract B

Semiconductors are soilids whose resistivity lies between those of electrical conductors and insulators. Semiconductors are used in computers, in radio and TV receivers, and in other electronic products.

Semiconductor devices perform many control functions. They may be used as rectifiers, amplifiers, detectors, oscillators and switching elements. Some characteristics, which make the semiconductors such an attractive member of the electronics family are the following:

1. Semiconductors are small and light in weight.

2. Semiconductors are solids. There is therefore little chance that elements will vibrate. Element vibration in vacuum tubes was the cause of microphonics.

3. Semiconductors require little power and radiate less heat than tubes. They do not need warm up time and operate as soon as power is applied.

4. Semiconductors do not undergo the chemical deterioration which occurs in tube cathodes. The deterioration of tube cathodes eventually results in unacceptable tube performance.

Silicon is the material of which most semiconductor devices are presently constructed.

21. In Russian write a content-based summary of the text you have translated.

  1. Translate into English the summary made in ex.20 of the text you haven’t read.

  1. Make a reverse written translation (from Russian into English) of the extract you have translated.

  1. Serve as simultaneous interpreter. Make an oral reverse interpretation of the text.

25. Find more information about semiconductors and tell your group mates.

UNIT VI

INTRINSIC SEMICONDUCTORS

Language Work

Past Simple Passive

Affirmative

I/he/she/it/we/you/they

was/were

tested

For example:

  • The Statue of Liberty was designed by a French engineer. =

= A French engineer designed the statue of Liberty.

  • Copper was discovered long ago.

Negative

I/he/she/it/we/you/they

was not/were not

tested

For example:

  • Alex was not taught English at school.

Questions

Was/Were

I/he/she/it/we/you/they

tested?

For example:

  • Was the first robot designed in the 20th century?

Positive

Negative

Question

The device was tested yesterday.

The device was not tested yesterday.

When was the device tested?