Основы английского языка для судовых электриков - страница 23
4. This is the well known & fundamental law in electricity which makes it possible to determine the current flowing through a
.circuit when the resistance in the circuit & the potential difference applied to it are known. What Ohm discovered was that the ratio of the potential difference between the ends of a.metallic conductor & the current flowing through the metallic conductor is a constant. The proportionality constant is the electj&fcal resistance. Symbolically, Ohm’s law is often written I - V/R
5. If any two of the three quantities : resistance, current & potential difference are known for a circuit, the third can always be determined by substituting in Ohm’s law.
22. /2 мин./ Внимательно слушая или просматривая следующие пары словосочетаний, записывайте номера, в которые включены идентичные пары слов.
1) make up - make up; 2) walk out - watch out; 3) fine loss -fire loss; 4) hold right - hold tight; 5) fast train - fast train; 6) take time - take nine; 7) small house - small hours; 8) fall down,- call down; 9) talk softly - talk softly; 10) to write back - right back; 11) bus stop - bus top; 12) thick fog - thick fog; 13) short visit - short visit; 14) empty pen - empty pan
23. а) Прослушайте описание электрических цепей. Постарайтесь понять и описать электрическую цепь, используя рисунок 3. б) Парная работа. Поговорите со своим партнером о различиях в цепях “а” и “Ь”. Докажите, что в цепи “Ь” не может протекать ток. /Рис.З//8 мин./
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| Fig. 3. Electric circuit. |
This is a circuit. Its elements are a voltage source, a resistor & a conductor. A voltage source supplies current. A resistor reduces current. A conductor connects the elements of the circuit. Compare circuit “a” with circuit “b”. What’s the difference'between them? Current passes through circuit “a” while no current passes through circuit “b”. Circuit “b” has an open. No current through circuit “b” results from an open. An open & a short are troubles in a circuit. A trouble in a circuit may result in no current in it.
24. /4 мин./ Слушая условия задачи, запишите числовые данные. Решите обе задачи и назовите результат.
1. A 70-ohm resistance is connected to the circuit. How much is the voltage if the current equals 4 A? 2. How much is the current in the circuit if a 60 V source is connected to a resistance of 1,600 ohms?
25. / 2 мин./ Прослушав/прочитав текст, скажите, как называется закон, о котором идет речь.
This law might have been predicted from the principle of the conservation of energy. When you move a magnet toward a coil & thus induce a current in its windings the induced current heats the wire. In order to supply the energy to do this, you must do work in overcoming an opposing force. If the force did not oppose the motion, you would create energy. Thus the magnetic field of the induced current is seen to oppose the change. This law & the right hand rule can be used to determine the direction of an induced current.
26. /9 мин./ а) Прослушайте/прочтите ряд слов и словосочетаний и запомните их значения.
What’s wrong with your car? - Что случилось с вашей машиной?; to take to pieces - разобрать /машину/; to put it together собрать ее; gear box - коробка передач; to straighten the bumper
- выпрямить бампер; to check the pressure - проверить давление; to put right - правильно установить; windscreen wiper - стеклоочиститель лобового стекла; to give a thorough overhaul - провести тщательный осмотр; except - кроме.
б) Прослушайте/прочтите диалог о профилактике автомобиля, запомните его содержание.
Whafs Wrong with your Car?
A: Must you stay in your workshop all day long?
B: Oh yes! I must!
A: Why?!
В: I must take my car to pieces & put it together again.
A: May I help you with the work?
B: Certainly! You can open the gear box, & also straighten the bumper.
A: What else must you do?
B: Oh! Quite a lot. I must check the tyre pressure & put right the windscreen wipers &...
A; & what?
B; & give the car a thorough overhaul.
A; Fortunately you don’t have to do it every day!
