1、正版可修改PPT課件(中職）電子專業英語第15章教學課件Warming-upI.Can you point out the difference of the following pictures?II.Do you know what the following abbreviations or symbols stand for?IC LDRUnit 15 Bridge Circuit下一頁返回III.Talk about Bridge Circuit in English. And the following patterns you can use: What is the bridg

2、e circuit used for?What is the resistance ratios?How to get balanced?Can you give us some examples?Text Comprehension Bridge CircuitVarious types of special seriesparallel circuits, called bridge circuits are used to make measurements in electronic circuits.Note that zero volts appear between points

3、 A and B when the bridge is balanced. You will see this balance only when the ratios of the resistances in the left arm and in the right arm of the bridge are equal.Unit 15 Bridge Circuit上一頁下一頁返回For instance, observe Figure. In the left arm of the bridge, R1=10 and R2=20. In the right arm of the bri

4、dge, R3=50 and R4=100. If V applied is 150V, then R1 drops onethird of the voltage across the left arm of the bridge, or 50V (since it is onethird of the left arms total resistance). R2 drops the other twothirds of the 150 volts, or 100V.What is about the other arm of the bridge? The same 150 V is a

5、pplied across that arms 150, with R3(50) dropping onethird of the applied voltage, or 50 V, and R4 dropping twothirds of the applied voltage (R4=two thirds of the right arms total R), or 100V.Note the voltage differential between points A and B is zero. This is because point A is at a potential of +

6、100 volts with respect to the power supplys negative terminal. Point B is also at a +100 volts with respect to the power supplys negative terminal. Thus, the difference of potential between points A and B is zero volts, since they are at the same potential.Unit 15 Bridge Circuit上一頁下一頁返回This balanced

7、 condition (zero volts between points A and B) exists whenever the resistance ratios of the top resistor to bottom resistor in the left and the right arm of the bridge are the same. That is, Bridge is balanced when Vocabularyparallel n. 并聯balanced adj. 平穩的，平衡的balance n. 天平，平衡ratios n. 比，比率arm n. 臂，臂

8、狀物drops n. 電壓降Unit 15 Bridge Circuit上一頁下一頁返回series n. 串聯differential n. 差異measurement n. 測量exist vi. 存在，繼續存在bottom n. 低，底部 adj. 底部的Phrases and expressionsbridge circuits橋式電路make measurement測量resistance ratios電阻比difference of potential電勢差，電位差negative terminal負端voltage differential電壓差Unit 15 Bridge Ci

9、rcuit上一頁下一頁返回Notes1. minute此處不是名詞“分鐘為”; 而是形容詞，意為“微笑的”。2. much the same way as 與差不多一樣地3. 這個 “all”意為“大家；所有人”。4. be associated with意為“與.相關的（相聯系的）”。5. “Using a special device”為現在分詞短語作條件狀語，譯成“如果使用一種專門的設備”。I Choose the right answer from A, B, and C according to the text. 【 】1.What is bridge circuit? It is

10、 _.A. a series circuitB. a parallel circuitC. a series-parallel circuitUnit 15 Bridge Circuit上一頁下一頁返回【 】2. When the ratio of the resistances in the left arm and in the right arm of the bridge are equal _. A. the zero volts appearB. the zero resistance appearC. the R1 drops one-third the voltage acro

11、ss the left arm of the bridge【 】3. According to the text bridge is balance when _ .A. B. C. Not mentioned.【 】4.Bridge circuits are used to _ .A. communicationB. measurement C. Not mentioned.Unit 15 Bridge Circuit上一頁下一頁返回II True or false.1. Bridge circuits are special series-parallel circuits used to

12、 make measurements in electronic circuits.2. Bridge circuits are series circuits.3. This balance condition exists whenever the resistance ratios are the same.4. The balance condition exists when voltage between points A and B is zero. 5. The highest voltage appear between points A and points B when

13、the bridge is balanced.III Translate the following sentences.1. Various types of special seriesparallel circuits, called bridge circuits are used to make measurements in electronic circuits.2. Note that zero volts appear between points A and B when the bridge is balanced.Unit 15 Bridge Circuit上一頁下一頁

14、返回3. You will see this balance only when the ratios of the resistances in the left arm and in the right arm of the bridge are equal.4. The difference of potential between points A and B is zero volts, since they are at the same potential.5. This balanced condition (zero volts between points A and B) exists whenev