Exercises

1 Find synonyms

1) value	1) to apply
2) all	2) to join
3) to use	3) form
4) device	4) is called
5) to connect	5) instrument
6) shape	6) quantity
7) is named	7) whole

2 Find antonyms

1) positive	1) minus
2) internal	2) jointly
3) outside	3) negative
4) separately	4) inside
5) to leave	5) external
6) plus	6) inversely
7) directly	7) to come

3 Answer the following questions:

1. What does the simplest electric circuit consist of?

2. What is a function of the power source (the energy receiver)?

3. What kind of circuit do the conductors and receiver form?

4. What does the external circuit and the source possess?

5. How is the relationship of the magnitude of the emf and resistance of the whole circuit expressed?

4 Complete the following sentences using the words given below:

1. According to Ohm’s laws, _____ is directly proportional to the emf and inversely proportional to the _____ of the whole circuit.

2. The power _____ transforms mechanical or other energy into electromagnetic energy.

3. The energy _____ transforms the electric energy to other forms of energy.

4. The conductors and receiver form _____ circuit.

5. The value of _____ depends upon material, shape and dimensions of the conductors.

6. Ohm’s laws play a very important role in electrical _____.

Words: engineering, resistance, receiver, source, current.

3. Types of Current Word List

1. a flow [flou] потік, струмінь

2. a current [׳kΛrәnt] струм

3. provided [prә׳vaidid] за умови (що)

4. to step up [stepΛp] підвищувати

5. frequency [׳fri:kwәnsi] частота

6. a cycle [saikl] цикл

Exercise 1. Find equivalents:

1. to change the direction а. кількість циклів

2. to step up voltage в. постійний струм

3. direct current с. джерело постійної напруги

4. alternating current d. підвищити напругу

5. to flow in cycles e. змінний струм

6. a direct voltage f. змінювати напрямок

7. an electric circuit g. частота струму

8. 60 times per second h. протікати циклами

9. the number of cycles i. 60 разів у секунду

10. frequency of the current j.електрична схема

Read and translate the text:

Types of Current

Current is a flow of electricity through a circuit. There are two main types of current: direct and alternating. A direct current (d.c.) flows through a conducting circuit in one direction only. It flows provided a direct voltage source is applied to the circuit.

An alternating current (a.c.) is a current that changes its direction of flow through a circuit. It flows provided an alternating voltage source is applied to the circuit. Alternating current flows in cycles. The number of cycles per second is called the frequency of the current. In a 60-cycle alternating current circuit the current flows in one direction 60 times and in the other direction 60 times per second.

It is easy to transform a.c. power from one voltage to another by a transformer. Transformers are also used to step down the voltage at the receiving point of the line to the low values that are necessary for us.

When necessary a.c. can be changed into d.c. but this is seldom necessary.

Exercise 2. Find the correct variant. Remember it: