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7. Pair work. Tell your groupmate about mutual inductance. Let him/her put the questions of Exercise 6 to you and answer them.
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7. Pair work. Tell your groupmate about mutual inductance. Let him/her put the questions of Exercise 6 to you and answer them.
Unit Fifteen [15]
1. a) Cover the right column and read the English words. Translate them into Russian and check your translation.
b) Cover the left column and translate the Russian words back into English.
| device | [dɪ ˈ vaɪ s] | прибор |
| field | [fiː ld] | поле |
| loose | [luː s] | свободный, нежесткий |
| tight | [taɪ t] | плотный |
| self-inductance | самоиндукция | |
| to couple | [ˈ kʌ pl] | соединять, сцеплять |
| to separate | [ˈ sepə reɪ t] | отделять |
| to transfer | [træ nsˈ fə ː ] | переносить |
| therefore | [ˈ ð ɛ ə fɔ ː ] | поэтому |
2. Put down the words with the opposite meaning and translate them into Russian.
Model: inconstant - constant
| incompetent - | ________________ | inactive - | ________________ |
| incorrect - | ________________ | inconsistent - | ________________ |
| indirect - | ________________ | unable - | ________________ |
| indefinite - | ________________ | inability - | ________________ |
3. Put down Russian equivalents of these word combinations. Then translate them back into English.
| loose coupling - | _________________________________________ |
| tight coupling - | _________________________________________ |
| transformer coupling - | _________________________________________ |
| electromagnetic fields - | _________________________________________ |
Coupling
When circuits are indirect-inductively coupled energy is transferred from one circuit to another using electromagnetic field of the inductance through which a varying current is flowing. The coupling device is a transformer. It is not in series with the elements of the circuit, therefore the coupling is indirect. The transformer consists of two windings: the primary and the secondary. The primary circuit is connected to the voltage source, the secondary - to the load circuit.
The coupling may be tight and loose. In case the coils of the coupling element are close together, the coupling is tight. In case the coils are separated the coupling is loose. In the loose coupling the mutual inductance is small compared with the self-inductance.
4. Complete the sentences using the correct variant:
| 1. The circuit connected to the voltage source is called | a) the secondary circuit. b) the primary circuit. |
| 2. The circuit receiving its energy through a coupling is | a) the primary circuit. b) the secondary circuit. |
| 3. The function of a coupling element is | a) to separate the circuits. b) to transfer energy. c) to prevent a short between the circuits. |
| 4. When the coupling is tight | a) the coils are separated. b) the coils are close together. |
| 5. When the coils are close together | a) the coupling is loose. b) the coupling is tight. |
| 6. The circuits are indirectly coupled when | a) the coupling element is common to both circuits and is in series with their other elements. b) the coupling element is not common to the circuits and is not in series with their other elements. |
5. Complete these sentences using while. Follow the model on page 13.
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1. The circuit receiving energy is the secondary circuit ….
2. The coupling is loose when the coils are separated ….
3. When the coupling element is not common to the circuits and not in series with their elements, the circuits are indirectly coupled ….
6. Answer the following questions:
1. What type of circuit is called the primary?
2. What type of circuit is called the secondary?
3. What is the function of a coupling element?
4. What type of coupling is called loose?
5. What type of coupling is called tight?
6. In what case are the circuits directly coupled?
7. In what case are the circuits indirectly coupled?
8. What is the difference between a tight and loose coupling?
9. In what case should a coupling element be substituted?
7. Pair work. Draw a scheme of 1) a loose coupling, 2) a tight coupling. Describe the schemes to your groupmate.
Unit Sixteen [16]
1. a) Cover the right column and read the English words. Translate them into Russian and check your translation.
b) Cover the left column and translate the Russian words back into English.
| filter | [ˈ fɪ ltə ] | фильтр |
| bypass | [ˈ baɪ pɑ ː s] | шунт |
| choke | [tʃ ouk] | дроссель |
| high-pass | [ˈ haɪ pɑ ː s] | высокопроходной |
| low-pass | [louˈ pɑ ː s] | низкопроходной |
| to oppose | [ə ˈ pouz] | оказывать сопротивление |
| on the other hand | с другой стороны | |
| choke coil | дроссельная катушка | |
| bypass coil | шунтовая катушка | |
| bypass condenser | шунтирующий конденсатор | |
| high-pass filter | фильтр верхних частот | |
| low-pass filter | фильтр низких частот | |
| opposing coils | противодействующие витки | |
| opposed current | противоток |
Filters
This filter is used to separate direct current from alternating current. It consists of a capacitor and a choke coil. Direct current cannot flow through the capacitor since its insulators oppose the flow of direct current. Therefore, it flows through the choke coil. Its windings easily pass direct current through them. Alternating current, on the other hand, passes through the capacitor, since it cannot easily pass through the choke coil. In this way the direct and the alternating currents are separated.
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I. A high-pass filter is used to pass high frequencies and to prevent the flow of low frequencies. It consists of a condenser and an inductance coil. The condenser passes currents of high frequencies and opposes the flow of low frequency currents. Low frequencies must be returned to the source and the inductance coil is used for a bypass.
II. A low-pass filter is used to pass low frequencies and to prevent the flow of high frequencies. It consists of an inductance coil and a condenser. The inductance coil passes low frequencies and opposes the flow of high frequencies. To return the high frequencies back to the source, a condenser is used for a bypass. Its capacity opposes the flow of low frequencies through it.
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