Ex 2. Match the words on the left with the words on the right.

1. roughly proportional	1. прямое применение
2. resistive medium	2. изоляционные материалы
3. applied voltage	3. прямо пропорционально
4. semiconductor properties	4. толщина провода
5. inversely proportional	5. способ сопротивления
6. insulating materials	6. применяемое напряжение
7. wire thickness	7. сохранение энергии
8. adjacent wires	8. свойства полупроводника
9. conservation of energy	9. обратно пропорционально
10. straightforward application	10. смежные провода

Ex 3. Translate from Russian into English.

1. Если мы увеличим давление на воду, проходящую по трубе, то поток увеличится. 2. Поток будет прямо пропорционален давлению. 3. Простой анализ последовательных и параллельных соединений показывает, что сопротивление объекта пропорционально его длине и обратно пропорционально поперечному сечению. 4. Поэтому можно разговаривать по телефону через большое расстояние. 5. Из того, что мы знаем о законе Ома, можно вывести правила для последовательных и параллельных резисторов. 6. Тепловое явление, связанное с электричеством, проходящим через проводник, иногда называют законом Джоуля. 7. На самом деле, это просто последствие сохранения энергии. 8. Помните, что «падение напряжения» между двумя точками может быть как положительным, так и отрицательным.

Ex 4. Complete the following sentences.

1. If we increase the pressure of water going into a pipe … 2. … the proportionality constant will be different than for narrower pipes. 3. Ohm`s law states that … 4. … is the resistance, measured in ohms. 5. Simple analysis of series and parallel connections shows that … 6. … are resistors. 7. The amount of power lost in a wire is … 8. … is sometimes called Joule`s law. 9. It`s really just a consequence of conservation of energy and … 10. There are two famous “laws” of electrical engineering, known as …

Ex 5. Tell what you have learnt about:

a) Ohm`s law

b) resistors

c) “I- squared-R losses”

d) Joule`s law

e) Kirchhoff’s Voltage law

f) Kirchhoff’s Current law.

 

Part 2.

Text 2.1

Semiconductor

A semiconductor is a material that has an electrical conductivity due to flowing electrons (as opposed to ionic conductivity) which is intermediate in magnitude between that of a conductor and an insulator. Devices made from semiconductor materials are the foundation of modern electronics, including radio, computers, telephones, and many other devices. Semiconductor devices include the various types of transistor, solar cells, many kinds of diodes including the light-emitting diode, the silicon controlled rectifier, and digital and analog integrated circuits. Similarly, semiconductor solar photovoltaic panels directly convert light energy into electrical energy. In a metallic conductor, current is carried by the flow of electrons. In semiconductors, current is often schematized as being carried either by the flow of electrons or by the flow of positively charged "holes" in the electron structure of the material. Actually, however, in both cases only electron movements are involved.

Common semiconducting materials are crystalline solids but amorphous and liquid semiconductors are known. These include hydrogenated amorphous silicon and mixtures of arsenic, selenium and tellurium in a variety of proportions. Such compounds share with better known semiconductors intermediate conductivity and a rapid variation of conductivity with temperature, as well as occasional negative resistance. Such disordered materials lack the rigid crystalline structure of conventional semiconductors such as silicon and are generally used in thin film structures, which are less demanding for as concerns the electronic quality of the material and thus are relatively insensitive to impurities and radiation damage. Organic semiconductors, that is, organic materials with properties resembling conventional semiconductors, are also known.

Silicon is used to create most semiconductors commercially. Dozens of other materials are used, including germanium, gallium arsenide, and silicon carbide. A pure semiconductor is often called an “intrinsic” semiconductor. The electronic properties and the conductivity of a semiconductor can be changed in a controlled manner by adding very small quantities of other elements, called “dopants”, to the intrinsic material. In crystalline silicon typically this is achieved by adding impurities of boron or phosphorus to the melt and then allowing the melt to solidify into the crystal. This process is called "doping".