3. Find in the text the English equivalents:

практическое использование электричества, двигаться в металле, под действием электрического тока, постоянно менять направление, увеличивать напряжение, индуцировать электрический ток, уменьшать напряжение, термическая внутренняя энергия, электрический ток, поток электронов, постоянный ток, переменный ток, работать от генератора, иметь большое преимущество, поток заряженных частиц, электрон, вибрация электронов, ион, недостаток, проводящая цепь.

4. True or False?

1) In a metal there is a large number of electrons which are free and can move through the metal under the action of an electric force.

2) The flow of electrons through a conductor is similar to the tornado.

3) In a "direct" current (DC) the electrons do not flow along at all, they merely vibrate a short distance backwards and forwards.

4) The engineer has to control the current in order to control the heating, chemical and magnetic effects of electricity.

5) A direct current is used for lighting, heating and industrial purposes.

6) No one has ever seen an electric current.

7) A metal is made up of tiny crystals which are visible to the naked eye.

8) The charges are usually electrons, but may also be ions.

9) An electric current in a solid is due to the movement of ions along that solid.

10) If a high-speed electron is projected into a gas, it will collide with some of the molecules of that gas.

5. Answer the questions:

1) What is an electric current?

2) How many types of electric current do you know?

3) When can the free electrons move through the metal?

4) To what current is the term d. с applied?

5) How does an alternating current flow?

6) What do we call a "direct" current?

7) What type of current is used now for lighting, heating and industrial purposes?

8) How do we call a movement or flow of charges?

9) Tell about the current flow in solids. Liquids. Gasses.

6. Translate orally, and make it fast:

Поток воды в трубке, DC, вибрировать, visible, только в одном направлении, существование электрического тока, transformer, conduction, поток зарядов, conducting circuit, charge, постоянное движение, генератор, metal wire, возвращаться к начальной точке, advantage, ion, сталкиваться с некоторыми молекулами, resistance, AC, индуцировать, двигаться, постоянно менять направление, kinetic energy, electric force, батарея, pipe.

7. Find the match in the gap below:

Bombardment through the medium battery little loss of energy pipe depends upon

батарея трубка малая потеря энергии зависит от бомбардировка посредством

8. Compare and contrast dc and ac pointing out their properties.

This symbol is found on many electronic devices that either require or produce direct current. DC is commonly found in many low-voltage applications, especially where these are powered by batteries, which can produce only DC, or solar power systems, since solar cells can produce only DC. Most automotive applications use DC, although the alternator is an AC device which uses a rectifier to produce DC. Most electronic circuits require a DC power supply. Applications using fuel cells (mixing hydrogen and oxygen together with a catalyst to produce electricity and water as byproducts) also produce only DC.

This symbol is found on many electronic devices that either require or produce alternating current. AC is the form in which electric power is delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. In these applications, an important goal is often the recovery of information encoded (or modulated) onto the AC signal.