中職電子專業(yè)英語第11章教學(xué)課件

1、正版可修改PPT課件(中職）電子專業(yè)英語第11章教學(xué)課件Warming-upI. Can you point out the different components in the following picture?II.Do you know the meaning of the following phrases?1. alternating voltage2. electromotive force3. electromagnetic inductionUnit 11 Transformer下一頁返回III.Talk about the different parts of a tra

2、nsformer .And the following questions you can use:Do you know what an ideal single-phase transformer consist of?Could you tell me how many kinds of coils are used in a transformer?Could you tell me the relation between the primary and secondary coil?What is the function of a transformer?Does a trans

3、former have losses?Text Comprehension TransformerA transformer cannot be called a machine, for it has no moving parts. It is designed for changing the alternating voltages and alternating currents by means of magnetic induction without any change of frequency.Unit 11 Transformer上一頁下一頁返回A twowinding

4、transformer consists of two coils which are arranged so that the magnetic lines of force of one coil pass through the other. The alternating current in one coil induces an EMF in the other because of the alternations of the value of the coil current.To strengthen the magnetic field passing through t

5、he coils of a transformer. We generally use a closed core of iron. The coil to which the voltage is applied is known as the primary, while the one from which the induced voltage is obtained is known as the secondary. If the secondary has more turns than the primary, the transformer is called a stepu

6、p transformer in which the AC voltage of the secondary winding is higher than that applied to the primary winding. If the secondary has fewer turns than the primary, the transformer is called a stepdown transformer in which the AC voltage of the secondary winding is lower than that applied to the pr

7、imary winding. In a wellbuilt transformer, the product of the secondary voltage and the secondary current is almost equal to that of the primary voltage and the primary current.Unit 11 Transformer上一頁下一頁返回Using a transformer, it is possible for us to transform power at low voltage into an almost simi

8、lar amount of power at high voltage, and vice versa. So the necessary voltage conversion is accomplished by use of transformers.The power output of a transformer is less than the power input because of unavoidable losses. These losses include resistance losses in the primary and secondary windings a

9、nd losses in the core due to eddy current and hysteresis.Unit 11 Transformer上一頁下一頁返回Vocabulary Transformer n. 變壓器transform v.傳輸 design v. 設(shè)計conversion n.轉(zhuǎn)化 frequency n. 頻率accomplish v.完成 wind v. 纏繞unavoidable adj.不可避免的 coil n. 線圈loss n. 損耗 strengthen v. 加強eddy n.回旋，旋轉(zhuǎn) apply v. 施加，應(yīng)用hysteresis n. 滯后P

10、hrases and expressionsalternating voltage交變（流）電壓alternating current交變(流)電壓by means of以方式Unit 11 Transformer上一頁下一頁返回magnetic induction磁感應(yīng)core of iron鐵芯a step-up transformer升壓變壓器a step-down transformer降壓變壓器vice versa反之亦然Notes1. for 在這里是連詞，引導(dǎo)原因狀語從句。2. a two winding transformer 這里指由兩個線圈組成的變壓器，winding是分詞

11、做transformer 的定語。3. The coil to which the voltage is applied is known as the primary, 這里primary 指primary coil,即初級線圈。4. The coil to which the voltage is applied is known as the primary, while the one from which the induced voltage is obtained is known as the secondary. 本句中是介詞加關(guān)系代詞引導(dǎo)定于從句，修飾the coil.Un

12、it 11 Transformer上一頁下一頁返回5. A well-built transformer 意思是一個制作精良的變壓器。I Choose the right answer from A, B, and C according to the text. 【 】1.A transformer cannot be called a machine, for it has not _.A. moving partsB. moving elementsC. moving electrons【 】2. A transformer can be made according to the th

13、eory of _.A. alternating current.B. integrated circuitsC. electromagnetic induction【 】3. To strengthen the magnetic field passing through the coils of a transformer. We generally use.A. an air core.B. a closed core of iron.C. Not mentioned.Unit 11 Transformer上一頁下一頁返回【 】4. In a _ transformer, the los

14、ses is quite low.A. set-up B. set-down.C. well-built.【 】5. Using a transformer, it is _for us to transform power at low voltage into an almost similar amount of power at high voltage, and vice versa.A possibleB necessaryC unnecessaryII True or false.1. A transformer cannot be called a machine, for i

15、t has no moving parts.2. The power output of a transformer is more than the power input because of unavoidable losses.3. The transformer cannot be used to change the voltage of power.4. The transformer can transform a low voltage into a high voltage and vice versa. 5. If the secondary has fewer turn

16、s than the primary, the transformer is called a stepdown transformer.Unit 11 Transformer上一頁下一頁返回III Translate the following sentences.1. A twowinding transformer consists of two coils 2. If the secondary has more turns than the primary, the transformer is called a stepup transformer.3. In a wellbuilt transformer, the product of the secondary voltage and the secondary current is almost equal to that of the primary voltage and the primary current.4. The alternating current in one coil induces an EMF in the other because of the alternations of the value