to discover, phenomenon, non-magrietic disk, compass, to pivot /вращаться/, axis /ось/, pole, to locate, edge /край/, to rotate, to spin/вертеть, вращать/, to impart/наделять, сообщать/.
1. The principle of the induction motor was first discovered in 1824, when the following interesting phenomenon was shown: if a non magnetic disk & a compass are pivoted with their axes parallel, so that one or both of the compass poles are located near the edge of the disk, the compass will rotate if the disk is made to spin, or the disk will rotate if the compass is made to spin.
2. The direction of the induced rotation in one element is always the same as that imparted to the other.
21. /3 мин./ Прореагируйте соответствующим образом на каждое из услышанных/прочитанных заданий.
1. List the main parts of induction motors. 2. Explain hofv you arrive at the conclusion that a great majority of the motors used aboard ships are designed to operate on a-c. 3. Give the formula to determine the resistance of the conductor.
22. /4 мин./ Прослушайте/прочтите вопросы и дайте на них ответы.
1. What are in your opinion 5 advantages of induction motors over those of dc motors? 2. What is the principle of operation of induction motors? 3. What are the most common types 6Г motors?
23. /3 мин./ Прослушайте/прочтите три коротких информации и скажите, о каком типе двигателя идет речь в каждом из них.
A. The motors operate at synchronous speed for all values of load. There are several constructions of sifch machines, although they are usually manufactured in very small ratings.
B. The electrical power is conducted directly to the rotor through brushes & a Q^nmutator.
C. This motor is a sort of rotating transformer in which a stationary winding is connected to the a-c source, while the other winding receives its power by transformer action while it rotates.
24. / 12 мин./ Отработайте правильное чтение текста со словарем или имитируйте произношение и интонацию диктора на материале основного текста: а) 2-й абзац, следя по книге; б) 1,3,4, не глядя в текст. ^
25. / 3 мин./ Дважды прослушайте/прочтите и запомните диалоги.
1 А: I intend to develop a theory explaining nuclear forces.
B: Is that all? It’s rather ambitious, isn’t it?
A: Ambitious? Naturally. It is the most ambitious project I can think of. You see, I have no time for anything else.
2 A:. Here is the application. Fill it out now, sign it & I’ll present it personally to the committee?
