Vocabulary:

to induce – побуждать, индуктировать

rate – темп

to cut (cut, cut) – выключать

to thread – пронизывать

coil – эл. катушка

to liberate – освобождать

ratio – отношение, пропорция

definition – определение

watt – ватт

ampere – ампер

volt – вольт

voltage – вольтаж

electromotive – электродвижущий

potential – потенциальный

coulomb – кулон

1. The Law of Electromagnetic Induction.

Faraday’s Law.

1. The induce E.M.F. (electromagnetic field) in a conductor is proportional to the rate at which the conductor cuts the magnetic lines of force.

2. The inducted E.M.F. in a circuit is proportional to the rate of change of the number of lines of the force threading the circuit. The induction coil, the dynamo, the transformer, and the telephone are practical applications of electromagnetic induction.

Faraday’s Law.

1. The weight of a substance liberated in electrolysis in proportional to the quantity of electricity passed.

2. When the same quantity of electricity is passed through different electrolytes, the weights of substances liberated are in the ration of their equivalent weights. Quantity of electricity is measured in coulombs, the product of the current in ampere, and the time in seconds.

2. Definitions of terms.

1. Watt is the unit of power.

2. Ampere is the unit of the flow of electric current.

3. Ampere-hour. The practical unit of quantity of electricity flowing per hour through a conductor when the current in it is one ampere. It is equal to 3600 coulombs.

4. Volt is the unit of electromotive force and potential difference.

5. Voltage is the electromotive force of a supply of electricity, measured in volts.

Text 10. ELECTRIC POWER. RELAYS

1. Прочтите и переведите.

Vocabulary:

relay – реле

to design – конструировать, проектировать

armature – арматура

spring – пружина

auxiliary – вспомогательный

winding – обмотка

to move – двигаться

to pull – тянуть, тащить

manually – ручным способом

primary – первичный

to actuate – побуждать

Electric power is generated at power plants and it must be transmitted to other parts of the country. How is current transmitted to those parts? Thick wires carry electric power over long distances. The wires are not always made of copper, often they are made of other metals. A number of wires put together form one thick cable. A cable consists of a number of wires put together and a pair consists of two insulated conductors forming a metallic circuit. Thus the basic transmission element of communications is a long transmission line, and a cable is the main part if this long transmission line.

Relays are electromagnetic devices widely used in various branches of industry. Relays are designed for rather low currents and for operation in control circuits at low voltages. The relay is placed close to the motor, which is connected to its secondary circuit. By means of a relay, electric current flowing in one circuit can open or close a second circuit and thus control the switching on and off a circuit. The main components of a relay are an electromagnet, an armature and a spring. As to contacts, they belong to its auxiliary elements. When a current starts flowing in the electromagnetic winding, the armature moves and the spring closes the contacts. When there is no current in the primary circuit, the spring pulls the armature and contacts open. The primary circuit is opened either manually and automatically. Every evening and morning street lights are switched on and off from the main panel by means of relays.

2. Ответьте на вопросы по тексту:

1. Where is electric power generated?

2. What is the main part of the transmission line?

3. Where are relays used?

4. What main parts does a relay consist of?

5. When does the armature begin to move?

6. When does the spring close the contact?

7. What happens to the contacts when there is no current in the primary circuit?

3. Дайте английские эквиваленты русских слов в скобках:

1. (Ряд) wires forms one thick cable.

2. (Пара) consists of a number of insulated conductors.

3. (Кабель) is (главная часть) of this transmission line.

4. (Таким образом) a cable (состоит) a number of wires put together.

5. (Изолированные проводники) form a part of an electric circuit.

4. Подберите нужное слово, переведите:

1. Modern methods of communication (produce, use) electric power.

2. Electric power (is developed, is generated) at power plants.

3. New powerful stations (were being built, were being produced) on the Volga for two years.

5. Выберите правильный вариант ответа:

1. Relays are designed for …

1. low current b) high current

2. A relay consists of …

1. a spring and an armature b) an electromagnet, an armature and a spring

3. The relay is placed..

1. close to the motor b) far from the motor

4. The motor is connected to …

1. the primary circuit b) the secondary circuit

5. Street lights are switched on and off …

a) by means of relays b) by means of controllers