中职电子专业英语第17章教学课件

1、正版可修改PPT课件(中职）电子专业英语第17章教学课件Warming-upI. Answer the following questions 1) We can found electric motors in our household appliances, Can you list some? , 2)How many types of motors can be divided according to the construction and the type of the power supply?3)For what purpose are d. c. motors used?

2、Text ComprehensionELECTRIC MOTORS An electric motor uses electrical energy to produce mechanical energy. The reverse process, that of using mechanical energy to produce electrical energy, is accomplished by a generator or dynamo.Unit 17 ELECTRIC MOTORS下一页返回Electric motors may be divided into three g

3、roups according to their construction and type of power used: universal, A.C (alternating current) and D.C(direct current). Universal motors, which can be operated on either a.c. or d.c. power, are usually less than 1/25 horsepower. They are used to operate small appliances and hand tools.Electric m

4、otors, both a.c. motors and d.c. motors, come in many shapes and sizes. Some are standardized electric motors for general-purpose applications. Other electric motors are intended for specific tasks. In any case, electric motors should be selected to satisfy the dynamic requirements of the machines o

5、n which they are applied without exceeding rated electric motor temperature. Thus, the first and most important step in electric motor selection is determining load characteristics - torque and speed versus time. Electric motor selection is also based on mission goals, power available, and cost.Unit

6、 17 ELECTRIC MOTORS上一页下一页返回Vocabulary1. motor n 发动机，马达 12 standardize vt.规范化，统一2. mechanical adj 机械的，导电的 13. intend vt 计划，打算3. reverse. adj 相反 14. select vt 挑选，选择4. accomplish vt.完成，做成 15. dynamic adj 引起移动的5. generate vt. 产生 16. exceed vt 超过，超出6. dynamo n. 发电机 17. selection n 电压7. construction n 构造，

7、结构 18. torque n. 扭距，转距8. universal adj 通用的，一般的，普通的 19. versus prep 与 相对，与相比9. appliance n. 用具，器具，装置 20. mission n. 任务，使命10. horsepower n马力 21 available 可用的；有效的11. characteristics n 特征、特性Unit 17 ELECTRIC MOTORS上一页下一页返回Phrases and expressions1.divide into 把分成 2.according to 根据，按照 3.either or 或者，或者4. i

8、n any case在任何情况下5. satisfy the requirements of满足要求 6. base on以为基础Notes1Universal motors, which can be operated on either a.c. or d.c. power, are usually less than 1/25 horsepower.Which 在此引导的是非限制定语从句，代表了先行词universal motors。非限制定语从句和主句的关系并不密切,使主句多一层意思,没有它主句也能独立存在,而且意思仍然清楚。这种从句和主句之间通常用逗号分开。例如: The most

9、important form of energy is electric energy ,which is widely used in our everyday life.(最重要的能量形式是电能，它广泛地用于我们的日常生活中)Unit 17 ELECTRIC MOTORS上一页下一页返回2both.and 用于两者之间，意思为“两者都”。全句译为：电动机，无论是直流电动机还是交流电动机，有多种形状和尺寸。I. Choose the right answer from A, B, and C according to the text. 【 】1. An electric motor use

10、s electrical energy to produce _ A. heat energy B. mechanical energyC. chemical energy【 】2. The reverse process, that of using mechanical energy to produce electrical energy, is accomplished by a _or dynamo. A. energy B. switch C. generator 【 】3. Electric motors may be divided into _ groups.A. one B

11、. three C. many 【 】4. Some are standardized electric motors for general-purpose applications._ electric motors are intended for specific tasks.A.Some B. many C. otherUnit 17 ELECTRIC MOTORS上一页下一页返回【 】5. Electric motor selection is also based on mission goals, power available, and._A.cost B value C.

12、temperature II. True or false.1.The process of using mechanical energy to produce electrical energy, is accomplished by an electric motor 2. Electric motors may be divided into two groups according to their construction and type of power used: A.C (alternating current) and D.C(direct current).3 Univ

13、ersal motors are used to operate large appliances and hand tools.4. The first and most important step in electric motor selection is determining load characteristics - torque and speed versus time5. Sometimes electric motors should be selected to satisfy the dynamic requirements of the machines on w

14、hich they are applied without exceeding rated electric motor temperature.Unit 17 ELECTRIC MOTORS上一页下一页返回III .Translate the following sentences.1. An electric motor uses electrical energy to produce mechanical energy2. Electric motors, both a.c. motors and d.c. motors, come in many shapes and sizes.3. Some are standardized electric motors for general-purpose applications 4. In any case, electric motors should be selected to satisfy the dynamic requirements of the machines on which they are applied without exceedin