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Contents

Unit 1. Ohm’s Law

Unit 2. Current Flow

Unit 3. Instruments and Measurements

Unit 4. Magnetism

References

p. 2

p. 11

p. 19

p. 28

p. 36

p.

p.

Unit 1

1. Read the text and find the answers to the following questions.

1. How is Ohm’s law stated?

2. What formula can Ohm’s law be expressed by?

Ohm’s Law

We know that current is the amount of electrons flowing past a point every second and that a force known as the e.m.f. (or voltage) is pushing them. We also know that the conductor will try to oppose the current, by offering a resistance to the flow of electrons.

Ohm’s law, the means by which these three topics (current, voltage, resistance) are linked together, is probably the most important electrical concept that you will need to understand and is stated as follows: the current in a circuit is directly proportional to the voltage applied to the circuit, and indirectly proportional to the resistance of the circuit, provided that the temperature affecting the circuit remains constant.

Ohm’s law was named after the nineteenth-century German physicist Georg Simon Ohm, who researched how current, potential difference and resistance are related to each other.

In simple language we could rewrite Ohm’s law as follows: the amount of electrons passing by every second will depend on how hard we push them, and what obstacles are put in their way. We can prove this is true, because if we increase the voltage (push harder), then we must increase the number of electrons that we can get at the other end. Try flicking a coin along the desk. The harder you flick it, the further it travels along the desk. This is what we mean by directly proportional. If one thing goes up (voltage), then so will the other thing (current).

Equally we could prove that if we increase the resistance (put more obstacles in the way), then this will reduce the amount of electrons that we can get along the wire. This time put an obstacle in front of the coin before you flick it. If flicked at the same strength, it will not go as far as it did before. This is what we mean by indirectly proportional. If one thing goes up (resistance), then the other thing will go down (current).

Ohm’s law can be expressed by the following formula:

Ohm’s law is a very simple and useful tool for analyzing electric circuits. It is used so often in the study of electricity and electronics that it needs to be committed to memory by the serious student. There is a trick to remembering how to solve for any one quantity if the other two are given. First, arrange the letters V, I, and R in a triangle like this:

If you know V and I, and wish to determine R, just eliminate R from the picture and see what is left:

If you know V and R, and wish to determine I, eliminate I and see what is left:

Lastly, if you know I and R, and wish to determine V, eliminate V and see what is left:

If you are comfortable with algebra, all you need to do is commit V=IR to memory and derive the other two formulas from that when you need them.

2. Now read the text once again looking up any word you do not understand in a dictionary and answer the following questions.

1. What is the electric current?

2. What is the electromotive force?

3. What is the resistance?

4. What three topics are linked together in Ohm’s law?

5. What did Georg Simon Ohm research?

6. What example is given in the text to illustrate Ohm’s law?

7. What simple method for remembering Ohm’s law do you know?

3. Decide if these statements are true or false. Quote from the text to support your decisions.

1. In the nineteenth century the German physicist Georg Simon Ohm investigated the relationship between current, potential difference and resistance.

2. The resistance of a conductor is a measure of its opposition to the passage of an electric current.

3. According to Ohm’s law the current in a circuit is directly proportional to the resistance of the circuit.

4. From the Ohm’s law formula we can say that the current in a circuit is indirectly proportional to the voltage applied to the circuit.

5. The more the resistance of the circuit, the less the current.

6. The more the voltage, the more the current.

Pronounce correctly

4. Read the following words with qu:

[kw] question, quote, square, equal, equality, quiz, equipment, quite, quiet, squirrel, quirk, queen, quid, quit, quick, equivalent;

[k] briquette, bisque, toque.

5. Read the words given below paying special attention to the ending –ing.

Flowing, pushing, following, affecting, writing, omitting, increasing, travelling, going, flicking, expressing, opposing, offering, referring, resisting, understanding, meaning, forcing.

6. Read the words paying attention to the stress :



offer

topic

increase

Simon

language

obstacle

concept

student



oppose

research

increase

reduce

provide

commit

arrange



probably

difference

equally

following

formula

analyze

memory



resistance

directly

remember

determine

Increase your vocabulary

7. Find these words and word combinations in the text and try to remember them:

affect

as follows

commit to memory

determine

directly proportional

eliminate

go down

go up

indirectly proportional

law

means

name after

obstacle

offer resistance to

oppose

point

prove

remain

research

solve for

state

strength

Prefixes say a lot

8. Make new words using the prefix re- that has the meaning do again and translate them.

Example: write – писати rewrite – переписати

Open, read, construct, new, distribute, charge, do, join, consider, appear, sell, pay, apply, number, lay, produce, production, cycle.

9. The prefixes in-, il-, im-, ir- give words the opposite meaning. Translate the words given below and use some of them in your own sentences.

Indirectly, invisible, indefinite, inefficiency, illogical, illegal, illiterate, impossible, immovable, impolite, immoderate, imperceptible, irrational, irregularity, irrotational, irreplaceable, irresponsible.

10. Match the words in A with the words which have similar meaning in B.

A. Every, to oppose, to link, to state, to mean, following.

B. Next, to resist, each, to imply, to connect, to formulate.

11. Match the words in A with their opposites in B.

A. Probable, directly, resistance, simple, true, up, similar, responsible, desirable, remember.

B. Down, conductance, undesirable, irresponsible, improbable, indirectly, false, forget, complex, dissimilar.

12. Put other, another, the other into the gaps.

1. Could you give me ____ example? 2. There is only one glove on the table. Where is ____? 3. He has ____ plans. 4. An electron and a proton attract each other because one is positive and ____ is negative. 5. The movement of free electrons from one place to ____ is referred to as current flow. 6. An object, which has gained 6.24 x 1018 electrons, has a negative charge of one coulomb. On ____ hand, an object, which has given up 6.24 x1018 electrons, has a positive charge of one coulomb. 7. The battery produces a negative charge at one terminal and a positive charge at ____ end. 8. Conductors are used to carry electricity from one place to ____.

Word range

13. Which sentence best illustrates the use of the word in italics taken from the text?

1. We know that current is the amount of electrons flowing past a point every second…

a. A voltmeter measures the potential difference between point A and point B.

b. Could you point a pencil, please?

c. I didn’t understand the point of his joke.

2. There is a trick to remembering how to solve for any one quantity if the other two are given.

a. I prefer quality to quantity.

b. V is a known quantity in this equation.

c. Jack has a very small quantity of English books.

Revise your grammar

Contact clauses

14. Translate the sentences with contact clauses.

1. We know like charges repel each other and unlike charges attract each other. 2. The molecules every substance consists of are in a state of constant motion. 3. What is the title of the book you have spoken about with you friend? 4. The book contains the electrical circuit data you will need to be familiarized with in order to carry out your work as an electrician. 5. Make sure power is disconnected before repairing any electrical device. 6. If a machine has low efficiency, this does not mean it is of limited use. 7. Metals we need for these experiments are semiconductors. 8. Farmers know energy savings on a farm mean more money in the farmer’s pocket. 9. If electrical equipment you are working with is damaged, do not use it. 10. We know electric potential is energy of an electric charge expressed in volts. 11. There are several devices you need to be careful of. 12. There are two categories materials may be divided into conductors and insulators.

15. Join each pair of sentences, making the subordinate clause a contact clause.

Pattern

I bought a book yesterday. It will help me solve this problem.

The book I bought yesterday will help me solve this problem.

1. You are working with a device. It is safe and reliable.

The device ____________________________________

2. We are going to visit a power station. It is situated in California.

The power station _______________________________

3. I want to use a device. Unfortunately it is out of order.

Unfortunately the device _________________________

4. The letter hasn’t arrived yet. I posted it three days ago.

The letter _____________________________________

5. Professor Brown lives in a house. It is very old.

The house _____________________________________

6. I have to use a machine in my job. It costs over a million pounds.

The machine ___________________________________

7. We live on the Earth. It is magnetic.

The Earth ______________________________________

8. Electricity is a form of energy. We use it every day.

The form of energy ______________________________

9. Most of the electricity is produced in our town. We use it.

Most of the electricity ____________________________

If, when + Past Participle

16. Translate the following sentences.

1. When asked she answered at once. 2. The magnetic characteristics of a material can change when alloyed with other elements. 3. If invited, we will go there. 4. In 1600 William Gilbert discovered that such things as glass, diamonds, and wax, when rubbed with a cloth, attracted light objects. 5. A permanent magnet will position itself in a north and south direction when freely suspended. 6. If given the book, read the article about electricity. 7. A permanent magnet is a material that, when inserted into a strong magnetic field, will not only begin to exhibit a magnetic field of its own, but also continue to exhibit a magnetic field once it has been removed from the original field.

17. Translate these sentences paying special attention to the verbal predicate.

1. The unit of power is the watt. 2. Hydrogen and helium atoms have one and two electrons. 3. Current is defined as the flow of electrical charge from one point to another. 4. A fuse is used to prevent overloading of electrical circuits. 5. In solids the current is carried by electrons. 6. James Clerk Maxwell wrote his first scientific work when he was fifteen years old. 7. Newton’s great book “Principia” was published in 1687. 8. An electric current is flowing through the conductor. 9. Any charge that is moving at some angle to the magnetic field is subject to a force. 10. Some specialists believe that oil will soon run out, perhaps even in the next 50 years. This means we will be using other sources of energy in the future. 11. The laboratory is being equipped with new instruments. 12. Electricity has been a subject of scientific interest since the 17th century. 13. If you have seen lightning or combed out your hair or rubbed a balloon on your head, you have experienced the effects of electrostatic charges. 14. The locations of the Earth’s magnetic poles have changed many times during the history of the Earth.

18. Complete the text with the correct form of the verb given in brackets.

Isaac Newton

Isaac Newton (1) ____ (be) born in 1642 in England. His father (2) ____ (die) two months before his birth. When Isaac was three his mother remarried, and Isaac (3) ____ (remain) with his grandmother. He was not interested in the family farm, so he (4) ____ (send) to Cambridge University to study.

Isaac was born just a short time after the death of Galileo, one of the greatest scientists of all time. Galileo (5) ____ (prove) that the planets revolve around the sun, not the earth as people thought at the time. Isaac Newton was very interested in the discoveries of Galileo and others. Isaac (6) ____ (think) the universe worked like a machine and that a few simple laws governed it. Like Galileo, he (7) ____ (realize) that mathematics was the way to explain and prove those laws. Isaac Newton was one of the world’s great scientists because he (8) ____ (take) his ideas, and the ideas of earlier scientists, and combined them into a unified picture of how the universe (9) ____ (work).

19. Use the correct form of the adjective in brackets. Translate the sentences.

1. I have ____ (little) time than he. 2. This is the ___ (short) way to the power station. 3. Yesterday I obtained ____ (far) information concerning this matter. 4. She was waiting for me in the ____ (far) corner of the park. 5. Silver is one of the ____ (good) conductors. 6. The ____ (bad) is over. 7. The ____ (small) the impedance (повний електричний опір), the ____ (great) the current for a given voltage. 8. The box must be as ____ (light) as possible. 9. The grass was twice as ____ (tall) as in the rest of the field. 10. Water is 800 times as ____ (dense) as air. 11. This device is twice as ____ (expensive). 12. The ____ (much) energy a substance has, the ____ (much) molecular movement there will be, and the ____ (high) the perceived temperature will be.

Unit 2

1. Read the text and find the answers to the following questions.

1. What kinds of circuits exist?

2. How is the total resistance in a combined circuit calculated?

Current Flow

In order for current to flow, two conditions must be met1. First, there has to be a potential difference (voltage) to force the current to flow and, second, there must be a continuous circuit (circle) for the current to flow around. When we start to look at circuits, we see that there are different combinations: series circuits, parallel circuits and parallel-series circuits.

If a number of resistors are connected together end to end and then connected to a battery, the current can only take one route through the circuit. This type of connection is called a series circuit (Fig. 1).

Fig. 1. Series circuit

If a number of resistors are connected together so that there are two or more routes for the current to flow, as shown in Figure 2, then they are said to be connected in parallel. In this type of connection the total current splits up and divides itself among the different branches of the circuit. However, note that the pressure pushing electrons along (voltage) will be the same through each of the branches. Therefore, any branch of a parallel circuit can be disconnected without affecting the other remaining branches.

Fig. 2. Parallel circuit

A series/parallel circuit combines the series and parallel circuits as shown in Figures 1 and 2. To calculate the total resistance in a combined circuit, we must first calculate the resistance of the parallel group. Then, having found the equivalent value for the parallel group, we simply treat the circuit as being made up of 2 series connected resistors and now add this value to any series resistors in the circuit, thus giving us the total resistance for the whole network.

Notes

1 to meet conditions – виконувати умови

2 treat the circuit as being made up of – розглядати коло як таке, що складається з

2. Now read the text once again looking up any word you do not understand in a dictionary and answer the following questions.

1. What two conditions must be met in order for current to flow?

2. What is a series circuit?

3. What is a parallel connection?

4. What does a series/parallel circuit combine?

3. Under the table there are six statements about circuits. Sort them into two groups under the following headings:

Series circuits

Parallel circuits

a. There is only one path for the current.

b. There are several paths for the current.

c. The current is not the same at all points in the circuit.

d. The current is the same at all points in the circuit.

e. The potential difference across each component is the same.

f. The potential difference across each component is usually different.

Pronounce correctly

4. Read the following words with the letter s:

[s] test, density, lists, pass, sun, start, see, some, scale, false, site;

[z] visit, position, resistor, branches, as, chosen, these, phase;

[] usually, visual, cohesion, adhesion, television, casual, Asia, corrosion.

5. Read the words given below paying special attention to the ending –tion.

Isolation, installation, protection, deflection, combination, inspection, connection, explanation, friction, condition, position, production, motion, definition, information, reflection, proportion.

Increase your vocabulary

6. Find these words and word combinations in the text and try to remember them:

a number of

branch

combine

connect

continuous

divide

network

parallel circuit

route

series circuit

show (showed, shown)

split up (split, split)

total

value

Suffixes say a lot

7. What part of the speech are these words? Translate them.

Temperature, agriculture, pressure, enclosure, manufacture, closure, composure, miniature, measure, structure, pleasure.

8. Complete the following sentences using the words from exercise 7.

1. Atmospheric ____ is high today.

2. The ____ of this series/parallel circuit is complex.

3. We are specialized in electrical engineering and computer technologies for ____.

4. The ____ is given in centimeters.

5. The ____.of energy saving devices is growing rapidly.

6. He can keep his ____.

7. It gives me great ____ to present the next speaker.

9. Match the words in A with the words which have similar meaning in B.

A. Among, to force, to split up, to affect, to combine, value, to treat, whole.

B. Quantity, to influence, total, to unite, to consider, to make, between, to divide.

10. Choose the word which best completes each sentence.

a. Measure b. measurement

c. measurable d. immeasurable

1. In the MKSA (meter-kilogram-second-ampere) system of units, length, mass, time and current are the fundamental ____ quantities. 2. Throughout history, many official systems of ____ have been used. 3. His contribution is ____, almost impossible to put into words. 4. To solve this problem it is necessary to ____ the resistance in the circuit.

e. Combine f. combination

5. Their invention is the ____ of power engineering and computer technologies. 6. These chemicals ____ with air to form a liquid.

11. Complete the passage using the following words and word combinations.

a. provides

b. low potential

c. generator

d. consist of

e. light and heat

f. current flow

g. which supplies electrical energy

h. electric circuit

i. conducts

j. converts

k. switch

l. in order to

Circuit Elements

Current moves from a point of high potential energy to a point of (1) ____. It can only do so if there is a path for it. This path is called an (2) ____. All circuits contain four elements: a source, a load, a transmission system and a control.

The source (3) ____ the electromotive force. This establishes the difference in potential which makes current flow possible. The source can be any device (4) ____. For example, it may be a (5) ____ or a battery. The load (6) ___ the electrical energy from the source into some other form of energy. For instance, a lamp changes electrical energy into (7) ____. The load can be any electrical device.

The transmission system (8) ____ the current round the circuit. Any conductor can be part of a transmission system. Most systems (9) ____ wires. The metal chassis of many electrical devices are used (10) ____ conduct current. Similarly, the body of a car is part of its electrical transmission system. The control regulates the (11) ____ in the circuit. It may limit the current, as does a rheostat, or interrupt the current, as does a (12) ____.

12. Put in order to or so that into the gaps.

1. ____ know which tool to use for which job, it is important to be familiar with the basic types of electro-technical systems. 2. He arrived early ____ he could work alone. 3. I always go to the library ____ find information. 4. Compressor, gas turbine and alternator (генератор змінного струму) are mounted on the same shaft ____ a part of mechanical power of the turbine can be utilized for the operation of the compressor. 5. I came here ____ get a good education. 6. The solar power station uses the Sun’s energy ____ produce electricity. 7. Several resistors are connected in parallel ____ there are several routes for the current to flow. 8. We need an electromotive force ____ drive electrons through a conductor. 9. Students gain their practical training at a farm ____ they improve their professional skills. 10. You should use Ohm’s law ____ solve this problem

Word range

13. Which sentence best illustrates the use of the word in italics taken from the text?

1. Therefore any branch of a parallel circuit can be disconnected…

a. Power engineering is a branch of electrical engineering.

b. A new branch appeared in the tree.

c. You should understand current division in a two-branch parallel circuit.

2. A series/parallel circuit combines the series and parallel circuits as shown in Figures 1 and 2.

a. He always combines the forces of all the team members.

b. Combines or combine harvesters are machines that both reap and thresh grains.

c. Hydrogen combines with oxygen to form water.

Revise your grammar

Complex Subject

14. Translate the following sentences.

1. The watt is known to be a unit of power. 2. Charles Coulomb is said to have measured attraction and repulsion of electrical charges quantitatively. 3. The battery is believed to be charging. 4. An electric current was found to flow between the electrodes. 5. When a coulomb of charge (or any given amount of charge) possesses a relatively large quantity of potential energy at a given location (location - ділянка), then that location is said to be a location of high electric potential. 6. And similarly, if a coulomb of charge (or any given amount of charge) possesses a relatively small quantity of potential energy at a given location, then that location is said to be a location of low electric potential. 7. If an object is moved, then work is said to have been done. 8. Conductors that let electricity flow freely are considered to have a high conductance and a low resistance. 9. Insulators that do not allow electricity to flow are known to have a low conductance and a high resistance. 10. The water seems to be boiling. 11. The delegation is reported to have left Kyiv. 12. He proved to be a good electrician. 13. This formula is thought not to be true for certain materials. 14. The resistance of materials in the superconducting state seems to be zero.

Phrasal verbs

15. Put one of the following phrasal verbs in its correct form into each gap:

a. break down

b. carry out

c. comb out

d. go down

e. go out

f. go up

g. heat up

h. name after

i. run out

j. split up

k. turn on

l. turn off

1. You should be a qualified specialist to ____ this work. 2. In order to ____ or ____ an electric light, we generally use a switch. 3. If one bulb breaks in a series circuit, all the lights ____. 4. If too much electricity flows, the fuse ____ and quickly melts. 5. The static electricity is made when you ____ your dry hair with a plastic comb. 6. Chemicals in the body ____ our food into useful substances. 7. Coal, oil, and gas can ____within 100 years or so. 8. Our University ____ academician Petro Vasylenko who devoted all his life to agricultural engineering science. 9. In a parallel circuit, the total electric current ____ among the different branches of the circuit. 10. If two quantities are indirectly proportional, it means that if one quantity ____ the other ____.

16. Translate these sentences paying special attention to modal verbs.

1. A magnetic field can pass through materials like air, water, paper, and glass. 2. Scientists think pigeons and bees are able to use the Earth’s magnetism to help them find their way. 3. A material that can be attracted by a magnet is called magnetic. 4. Electromagnets can be switched on and off. 5. Because it is difficult to store electricity, large quantities of it must be made as it is needed. 6. There has to be a potential difference to force the current to flow. 7. I ought to visit my parents more often. 8. May I smoke in the laboratory? 9. Only trained people were allowed to use this equipment. 10. Only students with the correct licences will be allowed to drive a vehicle. 11. We were to start work at 6. 12. You must come and see us.

17. Revise the infinitive functions and translate the sentences given below.

1. To carry electric charges by means of ions is the property of electrolytes. 2. To discover the electron was very important for electrostatics. 3. To conduct electric charges is the property of conductors 4. To obtain a larger electromotive force in a circuit, and hence to increase the current, cells can be arranged in series. 5. The heating effect of an electric current is used in fuses to safeguard circuits against excessive heating. 6. An ammeter must always be placed in a circuit so that the current to be measured flows directly through it.

Unit 3

1. Read the text and find the answers to the following questions.

1. What instruments are used for measurement of different electrical quantities?

2. What should electricians know for selecting the right instrument?