III. Translate these words and expressions.

a truck, to operate, to gear, an acceleration, a nucleus, a charge, a body, a conductor, a wire, a circuit, a current, a cell, electromotive force, a resistance.

IV. Finish the sentences.

1. The study of electricity may be divided………..

2. Magnetism is……….

3. Electrostatics is ………

4. Electrodynamics is… ………

5. A difference of pressure at the two ends of the pipe is…………….

6. Different substances differ………….

 

V. Ask questions to each part of the next sentence and learn the words.

 

In modern form a transformer consists of two coils of wire wound on a core of iron strips

 

VI. Translate the sentences

1. These scientists study living matter and its processes. They are biologists.

2. These scientists study the multitude of compounds of which matter is comprised. They are chemists.

3. These people study the earth's crust. They are geologists.

4. This material has equal numbers of positive and negative charges in its atoms. It is a conductor.

5. This electric conductor has a conductivity intermediate between that of an insulator and that of a metal. It is a semiconductor.

VII. Put the necessary prepositions.

The study of electricity may be divided... three branches: magnetism, electrostatics and electrodynamics.

1. Rubbing glass... silk produces static electricity.

2. Electrodynamics is the study... electricity in motion.

3. The flow of electricity... a conductor is analogous to the flow... water through a pipe.

4. Different substances differ... electrical conductivity.

5. The resistance is measured... the ohm.

 

VIII. Answer the next questions

1. What branches do you know of the study of electricity?

2. What is the magnetism?

3.  What is the electrostatic?

4.  What is the electrodynamics?

5. What has the electrical energy?

 

 

ПРАКТИЧЕСКАЯ РАБОТА № 20

ELECTRIC MOTORS.

Цель: Введение и активизация лексики по теме «Электрические моторы».

Оборудование: комплект тестов, раздаточный материал, иллюстрации по теме.

Vocabulary

I. Learn these words.

A variety	разнообразие, множество
shunt motors	эл.дв.с параллельным возбуждением (шунтовой эл.дв.)
Series motors	эл.дв.с последовательным возбуждением (сериесный)
Induction motors	асинхронный электродвигатель
To drive	управлять, приводить в движение
Ball-bearing	шар коподшипниковый
Fully-enclosed	полностью закрытый
Fan-cooled	Вентилируемый
Armature	Якорь
Field coils	Катушки
A winding	Обмотка
To pass through	проходить через что-либо
To be composed of	состоять из
A turn of thick wire	виток толстой проволки
Load	груз, нагрузка
Lo provide	Обеспечивать
A torque	вращающийся момент, пековой момент
To require	Требовать
A brush	Щетка
To apply	применять, относиться
Machine tools	металлорежущие станки
Lathe	токарный станок
To partake	иметь черты

 

 

II. Read the text. Translate and retell in Russian.

Electric Motors.

There is a wide variety of d.c. and ax. motors. There are shunt motors, series motors, synchronous motors, single, -two-, and three-phase motors. They are used to drive various machines.

Direct-current motors are of three principal kinds, and are named according to the manner in which their field coils are connected to the armature. They are named respectively: series, shunt, and compound.

In the series motors the field windings and armature are connected in series with each other. All the current which passes through the armature passes through the field coils. The field windings are therefore composed of a few turns of thick wire. Starting under heavy load, a series motor will take a large current to provide the huge torque required.

The field coils of shunt motors are connected direct across the  , hence they have the full voltage of the mains applied to term. The shunt motor may be called a constant speed motor, and is suitable for driving machine tools, lather, wood-working machines and any machines requiring a steady speed.

A compound motor has both shunt and series field windings and therefore partakes of the nature of both types of motors.