What Reagent Should Be Used To Carry Out The Following Reaction? Note: Draw Only One Structure.

SEMICONDUCTORS

There are materials that really occupy a place between the conductors of the current and the non-conductors. They are called semiconductors. These materials conduct electricity less readily than conductors but much improve than insulators.

Semiconductors include virtually all minerals, many chemic elements, a neat multifariousness of chemical compounds, alloys of metals, and a number of organic compounds. Like metals, they conduct electricity merely they do it less effectively. In metals all electrons are gratis and in insulators they are fixed. In semiconductors electrons are fixed, as well, but the connection is so weak that the oestrus motion of the atoms of a body easily pulls them abroad and sets them free.

Minerals and crystals appear to possess some unexpected properties. It is well known that their conductivity increases with heating and falls with cooling. As a semiconductor is heated, gratuitous electrons in it increase in number, hence, its conductivity increases also.

Heat is past no means the but phenomenon influencing semiconductors. They are sensitive to light, as well. Take germanium as an instance. Its electrical properties may greatly change when it is exposed to light. With the assistance of a ray of light directed at a semiconductor, nosotros can start or stop various machines, consequence remote control, and perform lots of other useful things. Just every bit they are influenced past falling calorie-free, semiconductors are also influenced by all radiation. Mostly speaking, they are so sensitive that a heated object tin can be detected by its radiation.

Such dependence of conductivity on heat and lite has opened up great possibilities for various uses of semiconductors. The semiconductor devices are applied for manual of signals, for automatic control of a variety of processes, for switching on engines, for the reproduction of sound, protection of high-voltage transmission lines, speeding up of some chemical reactions, and so on. On the ane hand they may exist used to transform light and oestrus free energy directly into electrical energy without any circuitous machinery with moving. parts, and on the other manus, they are capable of generating oestrus or cold from electricity.

Russian engineers and scientists turned their attending to semiconductors many years ago. They saw in them a means of solving an old engineering problem, namely, that of direct conversion of heat into electricity without boilers or machines. Semiconductor thermocouples created in Russia catechumen oestrus directly into electricity just equally a complex system consisting of a steam boiler, a steam engine and a generator does it.

Ii. Give the English equivalents for the words and word combinations beneath:

1) ��; ii) �� ; iii) ��; iv) ��; 5) ��; 6) �� (��); 7) ��; 8) �� ; 9) ��; 10) ��; 11) �� ; 12) �� ; 13) ��, ��; fourteen) ��; 15) ��; 16) �� ; 17) ��.

III. Guess the meaning of the following international words:

chemical element, organic, mineral, crystal, phenomenon, automatic, command, process, reproduction, conversion, banality.

IV. Bring together the beginnings and ends:

Semiconductors are sensitive to�	� conductors of the electric current and non-conductors.
Semiconductors catechumen heat into �	� dependence of conductivity on heat and low-cal.
Semiconductors occupy a place between �	� heat and lite.
Semiconductors conduct electricity	�into electricity without machines.
Great possibilities for diverse uses of semiconductors are connected with �	� less effectively than metals.
As a semiconductor is heated �	� its electrical conductivity increases as well.

5. Insert words and expressions:

1) Semiconductors include a corking diversity of (�� ), (�� ).

2) Minerals and crystals announced to possess some unexpected (��). Their electrical conductivity increases with (��) and falls with (��).

3) With the aid of a ray of light directed at a semiconductor, we tin can effect (�� ).

4) The semiconductor devices are applied for (�� ) of a variety of processes, for the (��) of audio, (��) of some chemical reactions.

five) (��) created in Russia convert estrus directly into electricity.

Half dozen. Answer the questions:

one) What practice semiconductors include? 2) How does the atomic construction of semiconductors influence their properties? 3) What phenomena influence semiconductors? 4) What are the semiconductor devices applied for? 5) How do semoconductors assist in solving engineering science problems?

VII. Talk on the backdrop of semiconductors and their practical application

UNIT 8

I. Read the text

ELECTRICITY AND MAGNETISM

TEXT 1

Electromotive Force

When free electrons are dislodged from atoms, electrical energy is released. Chemical reaction, friction estrus and electromagnetic consecration will cause electrons to move from one atom to some other. Whenever energy in any course is released, a force called electromotive (e. grand. f.) is developed.

If the forcefulness exerts its try always in ane direction, information technology is called direct; and if the strength changes its management of exertion periodically, it is called alternating. The chemical reaction in a dry cell, heat and friction are sources of a unidirectional strength. Electromagnetic induction produces an alternating strength. The direction of force depends on the direction in which the field is cut. Whenever an e. m. f. is adult, there is likewise a field of energy chosen an electrostatic field, which can exist detected by an electroscope and measured by an electrometer.

TEXT 2

Electromagnetic Induction

An electromotive force is induced in the conductor when at that place is a change in the magnetic field surrounding a conductor. This induced electromotive force may be produced in several ways every bit follows:

a. A usher may movement in a stationary magnetic field of abiding strength.

b. A stationary conductor may exist exposed 'to a moving magnetic field of constant strength.

c. The strength of the field surrounding the usher may modify without any motion of conductor or magnetic circuit.

The electromotive forcefulness induced by motility of a usher or a magnetic flux is the same when the conductor rotates and the flux is stationary or the flux rotates and the conductor is stationary. If both, conductor and flux, rotate in the same direction at the aforementioned speed, no electromotive force will be produced, if they rotate at the same speed only in contrary directions, the electromotive strength induced would be twice as that which would be induced, if 1 of them was stationary. An electromotive force is not induced when a conductor is moved parallel to the lines of force, but only when it moves at an angle with these lines.

Any motion beyond the direction of the lines, withal, will produce an electromotive force in the conductor. For this reason, the conductor is said to �cutting� the lines of force. The actual electromotive force induced in the conductor depends upon the nature at which the flux is cut.

TEXT 3

ELECTROMOTIVE FORCE AND RESISTANCE

The electromotive strength is the very force that moves the electrons from one betoken in an electric circuit towards another. In example this due east. m. f. is direct, the current is directly. On the other hand, were the electromotive force alternating, the current would be alternating, also. The due east. m. f. is measurable and information technology is the volt that is the unit of measurement used for measuring it. A electric current is unable to flow in a circuit consisting of metallic wires alone. A source of an east. g. f. should be provided as well. The source under consideration may be a cell or a battery, a generator, a thermocouple or a photocell, etc.

In addition to the electromotive forcefulness and the potential deviation reference should be made to another important factor that profoundly influences electrical menstruum, namely, resistance. All substances offer a certain corporeality of opposition, that is to say resistance, to the passage of current. This resistance may be high or low depending on the blazon of circuit and the fabric employed. Drinking glass and prophylactic offer a very high resistance and, hence, they are considered as good insulators. All substances do allow the passage of some current provided the potential departure is high enough.

Certain factors tin greatly influence the resistance of an electric excursion. They are the size of the wire, its length, and type. In short, the thinner or longer the wire, the greater is the resistance offered.

Ii. Give the English equivalents for the words beneath. Detect in the text the sentences with these words and translate them

i) ��; two) �� ; 3) ��; iv) �� ; 5) ��; 6) �� ; 7) �� ; viii) �� ; 9) ��.

3. Gauge the meaning of the following international words and translate them:

reaction, electrostatic, electrometer, electroscope, volt, metallic.

IV. Say whether these sentences are true or false:

1. Alternate force always exerts its effort in one management.

ii. Alternating force is produced by electromagnetic consecration.

iii. The electromotive force is induced by motion of a usher.

four. Resistance is an of import gene that greatly influences electrical menstruum.

5. The blazon of the material employed doesn�t influence the resistance.

V. Answer the questions:

1) What factors cause the motion of electrons from 1 atom to another? ii) When is the electromotive force developed? three) When does an electrostatic field appear? 4) How is the electromotive force induced? 5) What unit is used for measuring the electromotive force? six) What are the sources of electromotive force? 7) What is called �resistance�? 8) How practice the types of circuit and fabric influence the resistance? 9) Name the factors that influence the resistance of an electrical circuit.

UNIT ix

I. Read the text

Dynamos

The term �dynamo� is applied to machines which convert either mechanical energy into electrical free energy or electrical energy into mechanical energy past utilizing the principle of electromagnetic induction. A dynamo is chosen a generator when mechanical energy supplied in the form of rotation is converted into electrical energy. When the energy conversion takes place in the reverse order the dynamo is chosen a motor. Thus a dynamo is a reversible motorcar capable of operation as a generator or motor as desired.

A generator does not create electricity, only generates or produces an induced electromotive force, which causes a current to catamenia through a properly insulated system of electrical conductors external to it. The corporeality of electricity obtainable from such a generator is dependent upon the mechanical energy supplied. In the excursion external to a generator the e. one thousand. f. causes the electricity to menstruum from a higher or positive potential to a lower or negative potential. In the internal circuit of a generator the e. 1000. f. causes the current to flow from a lower potential to a higher potential. The action of a generator is based upon the principles of electromagnetic consecration.

The dynamo consists essentially of 2 parts: a magnetic field, produced past electromagnets, and a number of loops or coils of wire wound upon an fe cadre, forming the armature. These parts are arranged so that the number of the magnetic lines of force of the field threading through the armature, coils will be constantly varied, thereby producing a steady eastward. grand. f. in the generator or a abiding torque in the motor.

Ii. Fill in the gaps with the words given below:

to convert, generator, reversible, obtainable, induction, loops

1. The term �dynamo� is applied to machines which.....either mechanical energy into electric or on the opposite electric energy into mechanical free energy.

2. A dynamo is a..... machine capable of performance as a generator or motor as desired.

iii. The amount of electricity..... from such a generator is dependent upon the mechanical energy supplied.

4. The activity of a generator is based upon the principles of electromagnetic...... .

5. The dynamo consists of two parts: a magnetic field, produced by electromagnets, and a number of.....or coils of wire.

III. Find the Russian equivalents for the following English words and word combinations:

1) to be practical to smth.; two) to convert smth. into smth.; 3) rotation; 4) to utilise; 5) a properly insulated arrangement; 6) internal (external) excursion; 7) capable of operation; viii) positive (negative) potential; ix) reverse gild; ten) energy conversion.

Iv. Reply the questions

1. What term can be practical to machines converting mechanical free energy into electrical and vice versa?

2. What kind of machine is a dynamo?

iii. What is the function of a generator?

iv. What is the activity of a generator based upon?

5. What parts does the dynamo consist of?

V. Talk on the dynamo action

UNIT ten

I. Read the text

GENERATORS

The powerful, highly efficient generators and alternators that are in use today operate on the same principle as the dynamo invented by the corking English language scientist Faraday in 1831.

Dynamo-electrical machines are used to supply lite, heat and power on a large scale. These are the machines that produce more than 99.99 per cent of all the earth's electric power.

There are ii types of dynamos � the generator and the alternator. The one-time supplies d. c. which is similar to the electric current from a battery and the latter provides a. c. To generate electricity both of them must be continuously provided with energy from some exterior source of mechanical energy such as steam engines, steam turbines or water turbines.

A generator is an electric auto, which converts mechanical energy into electrical energy. At that place are straight-electric current (d. c.) generators and alternating-electric current (a. c.) generators. Their construction is much alike. A d. c. generator consists of stationary and rotating elements. The stationary elements are: the yoke or the frame and the field construction. The yoke forms the closed circuit for the magnetic flux. The part of the magnetic construction is to produce the magnetic field.

The rotating elements are: truthful armature and the commutator. They are on the aforementioned shaft. The armature consists of the core and the winding. The winding is continued to the commutator. With the help of the brushes on the commutator that behave the electrical current to the line the winding is connected to the external circuit. The stationary chemical element of an a. c. generator is called a stator. The rotating chemical element is chosen a rotor.

The essential departure between a d. c. generator and a. c. generator is that the former has a commutator by means of which the generated e. m. f. is made continuous, i. e. the commutator mechanically rectifies the alternating e. m. f. then that information technology is always of the aforementioned polarity.

D. c. generators are used for electrolytic processes such equally electroplating. Large d. c. generators are employed in such manufacturing processes as steel making. The d. c. generator of small capacities is used for diverse special purposes such as arc welding, automobile generators, train lighting systems, etc. Information technology besides finds rather extensive utilise in connection with advice systems.

II. Give the Russian equivalents for the following English words and word combinations:

1) generator; two) alternator; iii) steam turbine; 4) water turbine; 5) armature; 6) rotor; 7) stationary; 8) commutator; ix) stator; 10) yoke; 11) brushes; 12) core; thirteen) frame; 14) winding.

Three. Make full in the blanks

1. A generator is an electrical machine, which a) ----- mechanical energy into electrical energy.

2. A direct-current generator consists of b) ----- .

3. The dynamo was invented by c) ----- in 1831.

four. The d. c. generator is used for various purposes such as d) ----- .

Iv. Work out the plan of the text

V. Speak on the following points:

1. The structure of a generator.

ii. The directly current generators and their industrial awarding.

UNIT eleven

I. Read the text

Main Structural Elements of a D. C. Machine

A direct-current machine consists of two master parts, a stationary function, usually called the stator, designed mainly for producing a magnetic flux, and a rotating function, called the armature or the rotor. The stationary and rotating parts should be separated from each other by an air-gap. The stationary part of a d. c. machine consists of main poles, designed to create the main magnetic flux; commutating poles interposed betwixt the main poles; and a frame. It should be noted here that sparkless operation of the machine would exist impossible without the commutating poles. Thus, they should ensure sparkless operation of the brushes at the commutator.

The main pole consists of a laminated core the end of which facing the armature carries a pole shoe and a field coil through which direct current passes. The armature is a cylindrical body rotating in the infinite between the poles and comprising a slotted armature core, a winding inserted in the armature slots, a commutator, and a brush gear.

The frame is the stationary part of the machine to which are fixed the main and commutating poles and by ways of which the machine is bolted to its bedplate. The ringshaped portion which serves every bit the path for the main and commutating pole fluxes is chosen the yoke. Finish-shields or frame-heads which deport the bearings are too fastened to the frame.

Of these main structural elements of the motorcar the yoke, the pole cores, the armature core and the air-gap between the armature cadre and the pole core are known to form the magnetic circuit while the pole coils, the armature windings, the commutator and brushes should form the electric circuit of the machine.

Ii. Interpret the following phrases, using the given variants of translation:

to consist � �� : to consist of a stationary office and a rotating part;

separated � �� : the stationary and rotating parts should be separated from each other by an air gap;

to serve � �� -��: the ringshaped portion or yoke serves equally a path for the main and commutating pole fluxes.

III. Join the ancestry and the ends

Beginnings	Ends
The stationary parts of a d. c. machine are....	a laminated core the finish of which carries a pole shoe and a field ringlet.
The two chief parts of a directly electric current motorcar are....	main poles, commutating poles and a frame
The primary pole consists of....	A stationary office or stator and a rotating part, chosen the armature or the rotor.

Four. Arrange synonyms in pairs and memorize them:

a) to consist of; to be separated from; to create; to be interposed between; to pass; to rotate;

�) to be divided with; to produce; to introduce into; to permeate; to scroll; to revolve; to comprise.

5. Write out the names of the auto parts and describe their operational characteristics

UNIT 12

I. Read the text

The Alternator

The alternator is an electrical car for generating an alternating current by a relative motion of conductors and a magnetic field. The machine usually has a rotating field and a stationary armature. In a synchronous alternator the magnetic field is excited with a straight electric current. The direction of an induced eastward. m.f. is reversed each fourth dimension when a usher passes from a pole of ane polarity to a pole at some other polarity. Most machines of this type are used for lighting and power, but at that place are alternators with a revoking armature and a stationary field. They are used in small sizes mostly for special purposes.

Any electrical machine is reversible. When a machine is driven past a source of mechanical ability, it works as a generator and delivers electrical power. If information technology is connected to a source of electric power, it produces mechanical energy, and operates every bit a motor. The alternator may likewise be operated as a motor.

The a-c. generator, or alternator, does non differ in principle from the d. c. generator. The alternator consists of a field construction and an armature. The field structure is magnetized by a field winding carrying a. directly current. An electromotive force is generated in tine winding of the armature. In alternators the field is usually the rotating chemical element and the armature is stationary. This structure has a number of advantages. Only two rings are needed with a rotating field. These rings carry simply a relatively calorie-free field current, at a voltage generally of 125, and seldom exceeding 250. The insulation of such rings is not difficult. A stationary armature requires no skid rings. The leads from the armature can be continuously insulated from the armature winding to the switchboard, leaving no bare conductor. The alternator with a rotating field may be farther divided into the vertical and the horizontal types.

The vertical type is usually applied for large water-wheel generators where it is desirable to mountain the water turbine below the generator. The more than common horizontal type is used with diesel and steam engine bulldoze. A low-speed alternator of this type is suitable for a diesel engine bulldoze, a loftier speed alternator is suitable for a steam turbine bulldoze.

Two. Course nouns, cogent devices with the assist of the suffix � or. Translate them

To alternate, to commute, to comport, to generate

Three. Read the text and write out the key words, characterizing the alternator

IV. Translate the following word combinations paying attention to the Participle 2

The leads from the armature can be continuously insulated from�.., the vertical type of alternator applied for large water-bike generator; alternators with a revoking armature and a stationary field used in small sizes by and large for special purposes; a car driven by a source of mechanical power; the management of an induced eastward. m. f. �

V. State 5 questions to the text

6. Points for discussion:

1. The structure of the alternator;

2. The awarding of the alternator.

UNIT thirteen

I. Read the text

The Induction Motor

An consecration motor like whatsoever other motor consists of a stationary part, the stator, and a rotating part, the rotor. The rotor of an induction motor is not connected electrically to the source of power supply. The currents which broadcast in the rotor conductors are the outcome of voltage induced in the rotor in the magnetic field fix by the stator. The rotor is fitted with a set up of conductors in which currants flow. Equally these conductors lie in the magnetic field produced by the stator, a force is exerted on the conductors and the rotor begins to revolve. The operation of the motor depends upon the production of a rotating magnetic field. The speed at which the field of an consecration motor turns is called the synchronous speed of the field or of the motor.

The consecration motor is the simplest of the various types of electric motors and information technology has found more than extensive application in industry than any other type. It is made in two forms � the squirrel cage and the wound rotor, the difference being in the structure of the rotor.

The stator of the consecration motor has practically the same slot and winding organization as the alternator and has the coils arranged to grade a definite number of poles, the number of poles existence a determining factor in connectedness with the speed at which the motor volition operate. The rotor construction, however, is entirely different.

The squirrel-cage rotor is a simpler grade and has been used in many machines.

Instead of coils the winding consists of heavy copper bars.

The wound-rotor blazon has a winding fabricated up of well-insulated coils, mounted in groups whose finish connections are brought out to fill in rings. The purpose of this winding is to provide for variation in the amount of resistance included in the rotor circuit.

Provision for ventilation is made by leaving passageways through the core and frame, through which air is forced by fan vanes mounted on the rotor. In primary cases the motors now built in as an integral part of the machine it is to drive.

At that place being no electrical connection betwixt the rotor circuits of the consecration motor and the stator circuits, or supply line, the currents which flow in the rotor confined or windings correspond to the induced voltages, the action being similar to that of a transformer with a movable secondary. With only a single-phase winding on the stator, however, the torques produced in the 2 halves of the rotor would be in apposition, and the motor would not get-go. With more than one set of windings ii for a ii-phase motor, three for a three-phase motor a resultant field is produced which has the upshot of cutting across the rotor conductors and induces voltages in them. This field is considered to be revolving at uniform speed.

The term �revolving field� should not be taken to hateful bodily revolution of flux lines. The magnetic field from the coils of each phase varies in strength with changes in current value simply does not move around the stator. The revolutions are those of the resultant of the three, or two, phases, as the case may exist. A motor with a single-phase winding is not self-starting but must exist provided with an auxiliary device of some kind to enable the motor to develop a starting torque. The effect of the revolving field is the aforementioned as would result from actual revolution of a stator having direct-current poles. As voltages have been induced in the bars or windings of the rotor, currants outset flowing as a result of these voltages, and a torque is produced which brings the motor upwards to speed.

II. Discover in the text the English equivalents for the discussion combinations given below:

1) �� ; ii) �� ; 3) �� ; four) ��; 5) �� ; vi) �� ; 7) ��; eight) �� ; 9) ��; 10) �� .

III. Complete the following sentences co-ordinate to the contents of the text

1. The Induction Motor is ��.. of electric motors and is more than extensively practical in industry than any other type.

2. The purpose of this winding is ��.. for variation in the amount of resistance included in the rotor excursion.

3. The effect of �. is the aforementioned as would consequence from actual revolution of a stator having direct-current poles.

Iv. Answer the following questions:

1. What parts does the induction motor consist of?

ii. What are the names of its rotating and stationary parts?

3. What does the motor operation depend on?

four. How can the difference between stator and rotor construction be explained?

v. What does the term �revolving field� mean?

V. Translate the sentences from the text paying attention to the Nominative Accented Participle Constructions:

1. The consecration motor is made in two forms � the squirrel cage and the wound rotor, the departure existence in the construction of the rotor.

2. The stator of the induction motor has practically the same slot and winding arrangement every bit the alternator and has the coils arranged to form a definite number of poles, the number of poles being a determining factor in connection with the speed at which the motor volition operate.

3. There being no electrical connection betwixt the rotor circuits of the induction motor and the stator circuits, or supply line, the currents which flow in the rotor bars or windings stand for to the induced voltages, the activity existence similar to that of a transformer with a movable secondary.

Vi. Talk over the following points:

1) The construction of an consecration motor;

2) Induction motor operation principle.

UNIT 14

I. Read the text

Types of Induction Motors

TEXT 1

SINGLE � PHASE MOTOR

The single-phase induction motor differs from poly-phase type principally in the character of its magnetic field, as an ordinary single-stage winding volition not produce a rotating field, simply a field that is oscillating, and the induced currents and poles produced in the rotor by this field will tend to produce equal torque in contrary directions, therefore, the rotor cannot outset to revolve. Nevertheless, if the rotor can in some style exist fabricated to rotate at a speed respective to the frequency of the electric current in the stator windings and then the reaction of the stator and rotor flux is such as to produce a torque that will go along the rotor revolving.

In exercise the starting of single-phase induction motors is accomplished by iii general methods applicable to modest-sized motors only.

First: the carve up-stage method, in which an auxiliary stator winding is provided for starting purposes but, this winding being displaced from the chief stator winding by ninety electrical degrees. It has a higher inductance than the main stator winding, thus causing the currant in it to lag far plenty backside the electric current in the main winding to produce a shifting or rotating field during the starting menses, which exerts a starting torque on the rotor sufficient to crusade rotation.

When nearly normal speed has been reached the auxiliary winding is out of circuit past a switch and clutch in the motor, which operates automatically by centrifugal force, and the rotor continues to run as a single-phase motor. The starting torque of such motions being limited, they are frequently constructed with the rotor bundled to revolve freely on the shaft at starting until most normal speed is reached, at which time the load is pitched up by the automatic activeness of a centrifugal clutch.

Second: an auxiliary winding may be connected to the unmarried-stage line through an external inductance and a switch (for disconnecting the auxiliary winding from the circuit later on the motor has reached normal speed), the introduction of the inductance in the auxiliary winding splitting the stage as before.

TEXT 2

Three � PHASE INDUCTION MOTOR

The 3-phase induction motor is the most normally used type. It has been widely used in recent years. Normally an induction motor consists of a cylindrical core (the stator) which carries the primary coils in slots on its inner periphery. The primary coils are bundled for a three-stage supply and serve to produce a revolving magnetic field. The stator encircles a cylindrical rotor carrying the secondary winding in slots on its outer periphery.

The rotor winding may be one of two types: squirrel-cage and sideslip-band for wound-rotor). In a squirrel-cage machine the rotor winding forms a consummate closed circuit in itself. The rotor winding of a sideslip-ring car is completed when the slip rings are connected either direct together or through some resistance external to the machine. The rotor shaft is coupled to the shaft of the driven mechanism.

The rotor is stationary at some instant of time. The revolving magnetic field of the stator winding cuts across the stationary rotor winding at synchronous speed and induces an east. m. f. in it. The east. m. f. will give rising to a electric current which sets up a magnetic field. The rotor starts rotating.

It is the interaction between the rotor current and the revolving magnetic field that has created torque and has caused the rotor to rotate in the same direction as the revolving magnetic field. Tine speed of the rotor is 98�95 per cent of the synchronous speed of the revolving magnetic field of the stator. Hence another name for this blazon of motor is the asynchronous motor. Equally a matter of fact, the speed of the rotor cannot be equal to synchronous speed. If it were equal to the latter, the revolving magnetic field would not be able to cutting the secondary conductors and there would not be any current induced in the secondary winding and no interaction between the revolving field and the rotor current, and the motor would not run.