Unit I. Electric current and measurement. Types of electric circuits

Exercise 1. Read, practice and learn the following words and word combinations.

Electricity – електрика

electric current – електричний струм

matter – речовина

charge – заряд

conduct – проводити струм

conductor – провідник

electron – електрон

ion – іон

neutron – нейтрон

resistance – опір

battery – батарея (акумуляторна), акумулятор

electric appliance – електричний побутовий прилад

flashlight – ліхтарик

particle – елементарна частка

proton – протон

contain – вміщувати

stable – постійний

carbon – вуглець

diamond – алмаз

amber – янтар

flow – потік; текти

arrange – розташовувати

source – джерело

kick off – відштовхувати

attraction – тяжіння

tightly – щільно

measure – вимірювати

rubber – гума

potential difference – різниця потенціалів

power supply – джерело живлення

insulator – ізолятор (непровідник)

direct current (DC, d.c.)– постійний струм

alternating current (AC, a.c.)– змінний струм

Exercise 2. Read, translate and give the gist of text 1.

Text 1. Electric current

Electricity figures everywhere in our lives. Electricity lights up our homes, cooks our food, powers our computers, television sets, and other electronic devices. Electricity from batteries keeps our cars running and makes our flashlights shine in the dark.

Here’s something you can do to see the importance of electricity. Take a walk through your office, house or apartment and write down all the different appliances, devices and machines that use electricity. You’ll be amazed at how many things we use each and every day that depend on electricity.

But what is electricity? Where does it come from? How does it work? Before we understand that, we need to know a little bit about atoms and their structure.

All matter is made up of atoms, and atoms are made up of smaller particles. The three main particles making up an atom are the proton, the neutron and the electron.

Electrons contain a negative charge, protons – a positive charge. Neutrons are neutral – they have neither a positive nor a negative charge.

There are many different kinds of atoms, one for each type of element. An atom is a single part that makes up an element. There are 118 different known elements that make up every thing! Some elements are essential to life.

Each atom has a specific number of electrons, protons and neutrons. But no matter how many particles an atom has, the number of electrons usually needs to be the same as the number of protons. If the numbers are the same, the atom is called balanced, and it is very stable.

So, if an atom has six protons, it should also have six electrons. The element with six protons and six electrons is called carbon. Carbon is found in abundance in the sun, stars, comets, atmospheres of most planets, and the food we eat. Coal is made of carbon; so are diamonds.

Some kinds of atoms have loosely attached electrons. An atom that loses electrons has more protons than electrons and is positively charged. An atom that gains electrons has more negative particles and is negatively charged. A ‘charged’ atom is called an ‘ion’.

Electrons can be made to move from one atom to another. When those electrons move between them a current of electricity is created.

Scientists and engineers have learned many ways to move electrons off atoms.

Since all atoms want to be balanced, the atom that has been ‘unbalanced’ will look for electron to fill the place of the missing one. We say that this unbalanced atom has a ‘positive charge’ (+) because it has too many protons.

Since it got kicked off, the free electron moves around waiting for a balanced atom. The free electron charge is negative, and has no proton to balance it out, so that it has a ‘negative charge’ (-).

So what do positive and negative charges have to do with electricity?

Scientists and engineers have found several ways to create large numbers of positive atoms and free negative electrons. Since positive atoms want negative electrons so they can be balanced, they have a strong attraction for the electrons. The electrons also want to be part of a balanced atom, so they have a strong attraction to the positive atoms. So, the positive attracts the negative to balance out.

The more positive atoms or negative electrons you have, the stronger the attraction for the other. Since we have both positive and negative charged groups attracted to each other, we call the total attraction ‘charge’.

When electrons move among the atoms of matter, a current of electricity is created. This is what happens in a piece of wire. The electrons are passed from atom to atom, creating an electric current from one end to the other.

Electricity is conducted through some things better than in others. Its resistance measures how well something conducts electricity. Some things hold their electrons very tightly. Electrons do not move through them very well. These things are called insulators. Rubber, plastic, cloth, glass and dry air are good insulators and have very high resistance.

Other materials have some loosely held electrons, which move through them very easily. These are called conductors. Most metals – like copper, aluminum or steel – are good conductors.

In metallic conductors the charges are electrons. In liquids and gases the charges are ions. There are two types of electric current: direct current (DC) and alternating current (AC). The current flowing in a circuit is DC if it flows continuously in one direction. Current carries electrical energy from a power supply to the components of the circuit, where it is converted into other forms of energy. As compared to direct current, alternating current has several valuable characteristics. The most important of them is the fact that the voltage or the current may be varied to almost any desirable value by means of transformer. AC is used as a source of electric power both in industry and household.

Exercise 3. Identify (a) nouns, (b) adjectives, (c) verbal forms, (d) adverbs among the following words. Translate them.

Tightly, movement, balanced, conductor, continuously, direction, figure, usually, resistance, independently, electric, electricity, importance, make, difference, different, essential, special, specific, attached, positively, negatively, loosely, got, unbalanced, alternating, flowing, valuable.

Exercise 4. Form nouns from the following verbs by adding the following suffixes: -t(-ion), -ance, -ence, -ment, -or. Translate the pairs.

Move, direct, differ, resist, conduct, transform, measure, generate, connect, depend, attach, create, attract, insulate, create, develop, compare.

Exercise 5. Write derivatives of the following verbs, consult a dictionary if necessary. Translate the derivative chains.

Resist, conduct, use, connect, transform, convert, vary, differ, attract, insulate, contain.

Exercise 6. Give Ukrainian equivalents to the following word combinations.

The flow of charges, the current flowing in a circuit, the total resistance, the sum of resistances of individual components, to be used as a source of electric power, a specific number of, to be caused by, loosely attached, atoms of matter, created electric current, to be converted into other forms of energy, to flow alternately in each direction, electric energy, from a power supply to the components, electricity is conducted, any desirable value, move from one atom to another.

Exercise 7. Fill in the gaps with prepositions given below.

Through, to, of, in, on, by, off, from, among

1. An electric current is the flow … charges … a conducting circuit caused … a potential difference. 2. When electrons move … the atoms of matter, a current of electricity is created. 3. The electrons are passed … atom … atom, creating an electric current. 4. Electricity is conducted … some things better than … others. 5. Each branch … parallel circuits can be switched … or … independently. 6. Electrons spin around the centre, or nucleus, … the same way the moon spins around the Earth.

Exercise 8. Use the proper tense and voice form of the verb in brackets.

1. An electric current (be) the flow of charges. 2. Current (carry) electrical energy from a power supply. 3. The current (vary) to almost any desirable value by a transformer. 4. The way the electric current (flow) through (call) a circuit. 5. Rubber (not / allow) electricity (flow) freely. 6. Substances through which electricity easily (transmit) (call) conductors. 7. Copper (carry) the current more freely than iron.

Exercise 9. Translate the following sentences into English.

1. Електричний струм – це потік зарядів. 2. Електричний струм протікає, якщо є різниця потенціалів. 3. В металевих провідниках зарядами є електрони. 4. В рідинах та газах заряди – іони. 5. Електрон – це негативно заряджена елементарна частка, протон є позитивно зарядженою часткою. 6. Кожний атом має певну кількість електронів, протонів і нейтронів. 7. Вчені та інженери винайшли технології створення великої кількості позитивно заряджених атомів і вільних електронів. 8. Електричний струм вільно проходить через провідники. 9. Гума, пластмаса, скло, тканина мають високий електричний опір. 10. Струм, який протікає безперервно в одному напрямку, називається постійним струмом. 11. Змінний струм використовується як джерело електричної енергії як в промисловості, так і в побуті.

Exercise 10. Answer the questions on text 1.

1. What is an electric current? 2. What is the flow of charges through a circuit caused by? 3. How is resistance measured? 4. How do we call an atom that has the same number of electrons and protons? 5.What are insulators? 6. How do electrons behave in conductors?

7. Why are rubber, plastic, cloth and glass good insulators? 8. What is AC? 9. What is DC? 10. Why is AC widely used as a source of electric power in industry? 11. What is the function of a transformer?

Exercise 11. Put special questions to the following sentences.

1. Current carries electrical energy from a power supply to the components of the circuit. 2. A conductor can be heated by electric current. 3. Alternating current has several useful characteristics.

4. Electricity is conducted through some things better than in others.

5. The electrons are passed from atom to atom, creating an electric current.

Exercise 12. Read the following text and answer the question: ‘Where does the word electricity come from?’

‘Electrons’, ‘electricity’, ‘electronic’ and other words that begin with ‘electr…’ all originate from the Greek word ‘electror’, meaning ‘beaming sun’. In Greek, ‘electron’ is the word for amber.

Amber is a very pretty goldish brown ‘stone’ that sparkles gold and yellow in sunlight. Amber is actually fossilized tree sap! Millions of years ago insects got stuck in the tree sap. Small insects which had bit dinosaurs, had blood with DNA¹ from the dinosaurs in the bodies, which were now fossilized in the amber. Ancient Greeks discovered that amber behaved oddly – like attracting feathers – when rubbed by fur or other objects. They didn’t know what it was that caused this phenomenon. But the Greeks had discovered one of the first examples of static electricity. The Latin word ‘electricus’, means to ‘produce from amber friction’.

So, we get our English word electricity from Greek and Latin that were about amber.

1. DNA – (deoxyribonucleic acid) – ДНК.

Exercise 13. Read, practice and learn the following words and word combinations.

Current – струм

electron – електрон

wire – провід, дріт

copper – мідь; мідний; вкривати міддю

heat – тепло; нагрівати

heater – нагрівач

occur – виникати

cause – спричиняти

friction – тертя

rubber – гума

cord – шнур, трос

tower – вежа, опора

ampere (Amp) – ампер

difference – різниця

potential – потенціал

meter – вимірювальний пристрій

motor – двигун, мотор

transformer – трансформатор

transform – перетворювати

voltage – напруга

power – енергія

transmit – передавати

loss – втрата

advantage – перевага

reverse – рухатись у зворотному напрямку

cable – кабель

power line – лінія електропередач

Exercise 14. Read, translate and give the gist of text 2.