🔙 Quay lại trang tải sách pdf ebook Giáo trình tiếng anh Chuyên nghành điện Ebooks Nhóm Zalo SỞ GIÁO DỤC VÀ ĐÀO TẠO HÀ NỘI GIÁO D ỤC-BA O TẬ O w h A GIÁO TRÌNH SỞ GIẢO DỤC VÀ ĐÀO TẠO HẢ NỘI HỨA THỊ MAI HOA GIÁO TRÌNH TIẾNG ANH CHUYÊN NGÀNH ĐIỆN ENGLISH FOR ELECTRICAL ENGINEERING (D ùng trong các trường T H C N ) DẠĨ HỌC THÁI NGUYỀN I T P ĩ ĩ; í i . U ì U í i J.lfi 1-iV,' i / i t i i i NHÀ XUẤT BẢN HÀ NỘI - 2007 Lời giới thiêu 7V 7 ước ta đang bước vào thời kỳ công nghiệp hóa, hiện 1 V đại hóa nhằm đưa Việt Nam trở thành nước công nghiệp văn minh, hiện đại. Trong sự nglìiệp cách mạng to lớn đó, công tác đào tạo nhân lực luôn giữ vai trò quan trọng. Báo cáo Chính trị của Ban Chấp hành Trung ương Đảng Cộng sản Việt Nam tại Đại hội Đảng toàn quốc lần thứ IX đã chỉ rỗ: “Phát triển giáo dục và đào tạo là một trong những động lực quan trọng thúc đẩy sự nghiệp công nghiệp hóa, hiện đại hóa, là điều kiện để phát triển nguồn lực con người - yếu tố cơ bản để phát triển xã hội, tăng trưởng kinh tế nhanh và bền vững”. Quán triệt chủ trương, Nghị quyết của Đáng và Nhà nước và nhận thức đúng đắn vê tầm quan trọng của chương trình, giáo trình đối với việc nâng cao chất lượng đào tạo, theo đề nghị của Sở Giáo dục và Đào tạo Hà Nội, ngày 23/9/2003, Úy ban nhân dân thành phô' Hà Nội đã ra Quyết định số 5620/QĐ-UB cho phép Sở Giáo dục và Đào tạo thực hiện đê án biên soạn chương trình, giáo trình trong các trường Trung học cluiyén nghiệp (TH CN) Hà Nội. Quyết định này thể hiện sự quan tâm sâu sắc của Thành ủy, UBND thánh p h ố trong việc nâng cao chất lượng đào tạo và phát triển nguồn nhân lực Thủ đô. Trên cơ sở chương trình khung của Bộ Giáo dục và Đào tạo ban hành và những kinh ngliiệm rút ra từ thực tê đào tạo Sở Giáo dục và Đào tạo đã chỉ đạo các trường THCN tổ chức biên soạn chương trình, gicío trình một cách khoa học, hệ 3 thống và cập nhật những kiến thức thực tiễn phù hợp với đôi tượrìg học sinh THCN Hà Nội. Bộ giáo trình này ỉà tài liệu giảng dạy và liọc tập trong các trường THCN ở Hà Nội, đồng thời là tài liệu tham khảo hữu ích cho các trường có đào tạo các ngành kỹ thuật - nghiệp vụ và đông đảo bạn đọc quan tâm đến vấn đẻ hướng nghiệp, dạy nghề. Việc tổ chức biên soạn bộ chương trình, giáo trình này là một trong nhiều hoạt động thiết thực của ngành giáo dục và đào tạo Thủ đô đ ể kỷ niệm “50 năm giải phóng Thú đô ”, “50 năm thành lập ngành " và hướng tới kỷ niệm Ẫ'1000 năm Thăng Long - Hà N ộ i”. Sở Giáo dục và Đào tạo Hà Nội chán thành cảm ơn Thành ủy, UBND, các sở, ban, ngành của Thành phố, Vụ Giáo dục chuyên nghiệp Bộ Giáo dục và Đào tạo, các nhà khoa học, các chuyên gia đầu ngành, các giảng viên, các nhà quán lý, các nhà doanh nghiệp đã tạo điều kiện giúp đỡ, đóng góp V kiến, tham gia Hội đồng plìàn biện, Hội đổng thẩm định và Hội đồng nghiệm thu các chương trình, giáo trình. Đây là lần đẩu tiên Sở Giáo dục và Đào tạo Hà Nội tổ chức biên soạn chương trình, giáo trình. Dù đã hết sức cố gắng nhưiìg chắc chắn không tránh khỏi thiếu sót, bất cập. Chúng tôi mong nhận được những ý kiến đóng góp của bạn đọc đ ể từììg bước hoàn thiện bộ giáo trình trong các lần tái bản sau. GIÁM ĐỐC SỞ GIÁO DỤC VÀ ĐÀO TẠO 4 Lời nói đầu Giáo trình “English fo r electrical engineering ” dành cho học sinh và sinh viên chuyên ngành điện, được học tiếp sau khi đã học phần tiếng Anh giao tiếp. Vì lí do đó, nhiều phần ngữ pháp trong sách này đã không được nhắc lại. Là sách dành cho chuyên ngành, nên các từ trong sách đã được lặp đi lặp lại nhiều lần đ ể cho người học dễ nhớ từ hơn. Cấu tạo của cuốn sách gồm: 1. Vocabulary 2. Grammar 3. Reading comprehension 4. Exercises Phần từ vựng giúp người học nắm được từ trước khi vào các phần sau Phần ngữ pháp giúp người học biết thêm được một s ố kiến thức ngữ pháp có trong bài và giúp người học làm bài tập. Phần đọc hiểu củng c ố lại các từ mới và giới thiệu cách dùng của các từ mới trong đoạn văn. Phần bài tập có nhắc lại các từ có ở các phần trước giúp người học nhớ từ hơn. Trong giáo trình này tôi có tham khảo rất nhiều giáo trình của chuyên môn ngành điện. Tôi xin chân thành cám ơn các đồng nghiệp đã giúp đỡ tôi hoàn thành giáo trình này. TÁC GIẢ 5 Unit 1 ELECTRIC TOOLS (Dụng cụ điện) I. VOCABULARY Electric tool : dụng cụ điện combination pliers : kìm tổ hợp switch : công tắc cable shears : kìm/ kéo cắt cáp correctly : đúng cách thức, phù hợp installation : sự dặt (hệ thống máy móc, hệ thống sưởi..ệ) pincers : cái kìm bind : 1. trói, buộc, bỏ lại 2. ràng buộc 3ế kết lại với nhau wire : dây điện overhead (adj) : ỏ trên đầu, cao hon mặt đất nippers : cái kìm , cái kẹp terminal : ở giai đoạn cuối cùng core : điểm trung tâm , nòng c ố t, hạt nhân flexible :i. dẻo, mềm dẻo, dễ uốn 2. linh hoạt, linh động strip : tước , lột, lấy đi cord : dây thừng nhỏ, dây lead : chì, bằng chì 7 : kirn mui tron : do thiet bi; may moc : tron lan, pha tron : tuoc no vit : 1. danh, dap, 2. bat chay, chieu sang, 3. xuyen qua, tham qua : tho dien : phu , bao phu : mai sac : 1. thira nhan, phe chuan; 2. lam vung chac, cung co : xoi ranh, khia canh : ong ngoai, ong boc ngoai, mang xong : tuy theo, theo, y theo : sat han : mo cap, e to : ong din (nu6c, dau); cap dien : ren (dinh oc), xau thanh chu6i : ghe bang : hinh tam giac : cai ong : kim uon day : kim / keo cat cap : tay cam cach dien : dung cu xau xo cap : den pin : bang dinh cach dien : den day toe 8 long nose pliers apparatus blending screw driver strike electrician cover sharpen confirm groove sleeve according to soldering iron vise conduit threading bench triangle pipe hickey; conduit - blending pincers cable shears insulated handle threading apparatus electric/ pocket torch friction / insulating tape electric bulb fluorescent lamp : dèn huÿnh quang lighting fixture : bô dèn chiéu sang pendant switch : công tàc treo knife switch : càu dao diên fuse : càu tri cartridge fuse : eau tri ong socket : o càm two way socket : o càm hai ducmg plug : phich càm three- way multiple plug : phich càm ba ngâ extension cord : dây noi dài junction box : hôp dàu moi circuit breaker : âp tô mât, câi ngàt mach switch board :: bâng diên Three phrase asynchronous : dông co không dông bô ba II. GRAMMAR - What is this tool? - It is a fuse. - What are they? - They are scissors To call We call this tool an insulated handle We call these tools pliers To be called (+) This tool is called an electric bulb. These tools are called pincers (-) This tool isn't called a screwdriver These tools are not called conduit- blending pincers. (?) - Is this tool called a knife? - No, it isn't. - Are these tools called pliers? - Yes, they are. - What is this tool called in English? - It is called a switch. - What are these tools called in English? - They are called cable shears ffl. READING COMPREHENSION KIND OF TOOL AND USING TOOLS 1. Pincers 1. Using the tool as cut, joint and bind the wire. 2. Pincers are three types: 150mm, 175mm and 200mm. - 150mm: joint the small size - 175mm: for general electric work - 200mm: for overhead wire work. 2. Nippers 1. As the wire jointed the terminal it is cutting wire core. 2. Cutting the flexible wire, fine solied wire and shild wire, stripping the insulation cord wire and lead wire. 10 3. Long nose pliers 1. Holding the end of lead wire or stripping the insulation wire. 2. Making the terminal as joints the apparatus and blending the wire. 4. Wire strippers 1. It is automatic stripping the covered wire. 2. Confirm the size of wire core stripper find the same size groove with stripper. 5. Pressing pincers 1. Should be used to press ring sleeve and terminal, this should press on the metal, not on the insulation. 2. This should be pressed according to the wire sizes IV. EXERCISES Do the exercise Example: - What is this tool called in English? - It is called a screwdriver. - What are these tools called in English? - They are called condui -blendingpincers X 1. Scissors 2. Screwdriver 5. insulation- stripping pliers 6. Cable shears 12 7. T hreading apparatus 8a. Combination pliers 8b. Insulated handle h 9. Three- phase asynchronous 10. Electric/ pocket torch 11. Blow- lamp 12. Friction/ insulating tape 13 13. Electric bulb; filament lamp 14. Switch 17. Fluorescent lamp 18. Lighting fixture 19. Fuse 20. Cartridge fuse 21. Socket 22. Two-way socket 15 25. Extension cord 26. Junction box M jL m a in s OFF ON o; 27. Circuit breaker 28. Switch board 16 Unit 2 DESCRIBING SHAPES (Miêu tả hình dang) I. VOCABULARY Shape a rectangle (n) Circle (n) Rectangular (adj) Circular (adj) Describe (v) Object (n) Dimensional (adj) Triangle (n) Triangular (adj) Sphere (n) Spherical (adj) Semi-circle (n) Semi-circular (adj) Cylinder (n) Cylindrical (adj) Square(n) (adj) hình dạng hình chữ nhật hình tròn hình chữ nhật hình tròn miêu tả đồ vật, vật thể chiều, kích thước, cỡ hình tam giác hình tam giác hình cầu hình cầu hình bán nguyệt hình bán nguyệt khối trụ khối trụ : hình vuông 17 hình ống, ống, tuýp hình ống, ống, tuýp đuờng , dòng kẻ b ờ , gờ, cạnh đuờng thẳng đường cong, đường vòng đường tròn điểm nhọn thông thường hình dạng số học tính từ sóng nhận ra giống với nổi tiếng ăng ten sóng dạng răng cưa vị trí thành phần, phần hợp thành mạch đoạn từ mẫu, khuân mẫu điều chỉnh tụ diện cuộn dây chất bán dẫn mạch chỉnh lưu sức nóng, độ nóng 18 Tube (n) Tubular (adj) Line (n) Edge(n) Straight Curved Rounded Pointed regular geometric shape adjective wave recognize resemble well known antenna a saw - tooth wave position component circuit phrase pattern tuning capacitor coil semiconductor rectifier heat(n) sink : bon, thung ceramic : bang gom transformer : may bien ap laminations : su dat mong, sir can mong electrolytic : thuoc dien phan a magnet : nam cham a cable : day cap conduit : ong cach dien a carbon brush : choi carbon a motor : dong co pole : cuc, diem circ shoe : mieng bit, vat hinh giay a resistor : cai dien tro Wound round : cuon quanh Locate : nam, dat vi tri Connect : noi, ket noi Apply : ap vao Mount : leo, treo, lap rap, keo len Wire : mac day dien, bat dien core : loi piece : mau, mieng the collector : cai thu, thu nhat the base : 1. co so, nen tang, 2. ducfng feedback : sir hoan nguoc voltage : dien ap the shaft : true an iron core : loi sat Earth : dat, qua dat 19 II. G R A M M A R - What is this shape? - It is a rectangle. - What are these shapes? - They are circles - What shape is this door? - It is rectangular - What shape are these windows? - They are circular Describe the shapes of the objects: Shape Noun Adjective Shape Noun Adjective 2 dimensional 3 dimensional C circle circular sphere spherical D semi-circle semi-circular,_____Cylinder cylindrical square square C O tube tubular / / rectangle rectangular rectangular / lines Edges straight rounded ■'N . curved pointed When sometimes has a regular geometric shape we can use one of the adjective from the table to describe it . 20 Example : A square wave When the object has no recognized geometric shape but does not resemble a well known object or a letter of the alphabet, it may be describe in one of the following ways. Example: an H - shaped antenna a saw - tooth wave Describing position and connection When describing the position of a component or how it is connected in a circuit, phrases of this pattern are used: Be + past participle + preposition Example s 1. The tuning capacitor IS CONNECTED ACROSS the coil. ----- semiconductor I rectifier 2. The semiconductor rectifier IS MOUNTED ON the heat sink. 21 III. READING COMPREHENSION HOW BATTERY ARE CHARGED The filler plugs are removed and the battery is connected to the charger. It must be ensured that the correct polarity is observed and good connections are made. The charger is then switched on. The charger is switched off when the battery has been fully charged. The specific gravity of a sample cell is.checked. The filler plugs are replaced and the battery left to cool before use. IV. EXERCISES Exercisel What are these shapes? Example: 1. - What is this shape? - It is a circle 2 3 4 5 6 7 8 22 Exercise 2 Describe the shapes o f the following objects as completely as possible Example: 1. - What shape is a ceramic capacitor? - It is square (a)u (b) (c) (d) 1. a ceramic capacitor 2. transformer laminations _L 3. an electrolytic capacitor 4. an antenna 5. a magnet 6. a cable conduit 9. a motor pole shoe 10. a resistor Exercise 3 Describing position and connection When describing the position of a component or how it is connected in a circuit, phrases of this pattern are used: Be + past participle + preposition Example,s * 1. The tuning capacitor IS CONNECTED ACROSS the coil. sem iconductor rectifier 2. The semiconductor rectifier IS MOUNTED ON the heat sink. Now complete each sentence using an appropriate phrase from this list: Wound round located within Connected across applied to Mounted on connected to Wired to connected between pole 1. The bulbs a r e ........the battery 2. The core i s ..............the pole piece 25 27 pF rlH 3. The 27 pF capacitor is................ ........ the collector and the base. feedback 4. Feedback voltage is \k the base of the transistor through Cl rotor shaft 5. The antenna i s ..................the coil 6. The rotor i s .................. the shaft core 7. The coil i s .................an iron core + 8. The negative pole of the b attery ...................... earth. 26 Unit 3 MEASURING INSTRUMENTS (Dong ho do) I. VOCABULARY measure : do lucmg resistance (n) : diên trô resistors (n) : câi diên tro voltmeter : vôn ké ammeter : am pe ké connect : ket noi adjust : dieu chinh rheostat : câi bien tro scale : câi can deflection : sir lêch, su chêch huông, dô lêch simultaneous : dong thcd, xây ra cùng mot lue, làm cùng mot lue readings : su doc, su xem current : (diên hoc) dông diên carculate : tinh toân formula : công thurc repeat : nhâc lai tabulate : xép thành bàng, trînh bày thành bâng, 27 result : kết quả object : đồ vật, vật thể ohmmeter : ôm kế positive : dương tính charge : điện tích (nạp vào ắc quy), sự nạp điện, sự tích điện electrostatics : tĩnh điện học conductor : (vật lý) chất dẫn (điện , nhiệt) dielectric : (điện) chất điện môi piezoelectric : áp điện effect : (vật lý) hiệu ứng parallel connection: cách mắc song song series connection : cách mắc nối tiếp imperative mood : thức mệnh lệnh solder : hàn, hàn gắn transistors : bóng bán dẫn (dụng cụ điện tử nhỏ) heat : hơi nóng, sức nóng; sự nóng; (vật lý) nhiệt shunt : (điện học) mắc sơn; mạch mắc rẽ instruction : chỉ thị, lời chỉ dẫn infinitive : nguyên thể apparatus : đồ thiết b ị , máy móc description : miêu tả present passive : thì hiện tại giản đơn report : bản báo cáo; bản tường thuật; biên bản experiment : cuộc thí nghiệm, cuộc thử nghiệm past passive : thì quá khứ giản đơn 28 II. GRAMMAR Do this ! Do not ( Don’t) do that! Example: Imperative mood 1. Measure the collector current 2. Switch off the supply 3. Do not solder transistors without a heat- shunt. Simple instruction use the infinitive Write the instructions to measure the total resistance of resistors in parallel, using the circuit in figure 1. Connect up the apparatus as shown in figure 1. Describing an experiment Make a description of the first experiment by rewriting each instruction in the present passive. Example: 1. Use a high - resistance voltmeter and a low - resistance ammeter. -------►A HIGH - RESISTANCE VOLTMETER AND A LOW - RESISTANCE AMMETER IS USED Make a report of the second experiment by rewriting each of your instruction in the past passive 2. Connect up the apparatus as shown in figure 1. ------- ► THE APPARATUS WAS CONNECTED UP AS SHOWN IN FIGURE 1. 29 III. READING COMPREHENSION MEASURE THE TOTAL RESISTANCE OF RESISTORS w v \ ------^ * FIGURE 1 1. Use a high - resistance voltmeter and a low - resistance ammeter 2.Connect R1 across AB 3. Close the switch and adjust the rheostat until both meters show almost full scale deflection. 4. Take simultaneous readings of both voltage and current. 5. Calculate R1 by the formula R 6. Repeat this for R2 7. Connect R1 and R2 in series across AB . 8. Calculate the total resistance using the same formula as before. 9. Tabulate the results 30 IV. EXERCISES Exercise 1 Example: - What is this object called in English? - It is called an ammeter. 1. an ammeter 2. a voltmeter 3. an ohmmeter 4. positive charge 31 5. Electrostatic field 6. conductor € CC€ C€ CC€ € € C€ € € CCt) 7. dielectric 8. piezoelectric effect 8. parallel connection 10. Series connection Exercise 2 Imperative mood Do this ! Do not (Don’t) do that! Example: 1. Measure the collector current 2. Switch off the supply 3. Do not solder transistors without a heat- shunt. Look at the text 32 Simple instruction use the infinitive Write the instructions to measure the total resistance of resistors in parallel, using the circuit in figure 1. 1. Connect up the apparatus as shown in figure 1. 2 ................................................................................................................. 3 4 5 6 7 8 9 .................................................................................................................. Exercise 3 Describing an experiment Make a description of the first experiment in exercise 2 by rewriting each instruction in the present passive. Example: 1. Use a high - resistance voltmeter and a low - resistance ammeter. -------► A HIGH - RESISTANCE VOLTMETER AND A LOW - RESISTANCE AMMETER IS USED 1 ................................................................................................................................... 2 .................................................................................................................... 3 4 5 6 7 . 8 9 .................................................................................................................... 33 Exercise 4 Reporting an experiment Make a report of the second experiment in exercise 2 by rewriting each of your instruction in the past passive 1. Connect up the apparatus as shown in figure 1. -------► THE APPARATUS WAS CONNECTED UP AS SHOWN IN FIGURE 1 1...................................................................................................................................... 2 ..................................................................................................... 3 4 5 6 ........................... ;.................................... 7 .............................................. 8 9 .................................................................................................................... 34 Unit 4 ELECTRIC MATERIALS: CONDUCTORS, INSULATORS AND SEMICONDUCTORS (Vật liệu điện: Vật liệu dẫn điện, Vật liệu cách điện, \ • • • • • • • • ' Vât liêu bán dẫn) I. VOCABULARY conductor : vật liệu dẫn điện insulator : vật liệu cách điện semiconductor : vật liệu bán dẫn across : qua, ngang qua body : co thể movement : chuyển động free : tự do electron : điện tử towards : về phía be classified : đuợc chia ra, phân loại group : nhóm according to : theo, dựa theo, đi theo readily : dễ dàng permit : cho phép category : phạm trù, lĩnh vực 35 substances chat path du6ng din mangarin mang gan copper dong therefore boi vay, cho nen, vi the, vay thi widely rong rai non- metal khong chua kim loai liquid cha't long release tha long rubber cao su nylon ni Ion porcelain cha't sir however dii den dau, tuy the, tuy nhien be ignored 16 di midway a giua conditions dieu kien behave cu xu germanium ten mot chat ban dan silicon si li con mixtures h6n hop metallic (adj) kim loai oxides o xit act hoat dong thermistors chat cam ung nhiet, chat nhay nhiet temperature - sensing devices thiet bi cam ung nhiet rephrase tap hop lai tir rewrite viet lai 36 replace : dặt lại italic : viết nghiêng expressions : biểu hiện, diễn đạt passage : đoạn văn similar : giống thế meaning : ý nghĩa contextual reference : dựa theo ngữ cảnh pronouns : đại từ refer to : nói đến, dẫn đến, đua đến fact : hiện tuợng idea : ý tuỏng decide : quyết định statements : câu, câu nói true : đúng false : sai quote : lời trích dẫn, dấu ngoặc kép relative clause : mệnh đề quan hệ capitals : chữ viết hoa consumers : nguời tiêu dùng, nguời tiêu thụ domestic : (thuộc) gia đình, việc nhà, nội trợ quantities : luợng, số luợng, khối luợng intermediate : giữa, trung gian substations : trạm nhỏ value : giá trị distribution : phân phối reduce : giảm đi, giảm bớt, hạ require : đòi hỏi, yêu cầu illumination : sự chiếu sáng, sự rọi sáng (vật lý) độ rọi 37 assemble (kỹ thuật) lắp ráp precision comparatively detector rectify armoured rick damage II. GRAMMAR sự đúng đắn, rõ ràng, tính chính xác, độ chính xác tương đối (radio) bộ tách sóng (vật lý) chỉnh lưu (dòng điện xoay chiều) (radịo) tách sóng bọc sắt đống, đụm hỏng hóc If we connect a battery across a body, there is a movement of free electrons towards the positive end. All materials can be classified into three groups according to how readily they permit an electric current to flow. Relative clause 1 Study these sentences : 1. Starter motor brushes are made of carbon 2. The carbon contains copper. Both these sentences refer to carbon. We can link them by making sentence 2 a relative clause. Example: ----------►Starter motor brushed are made of carbon WHICH CONTAINS COPPER. The relative clause is in capitals. Note that the carbon in sentence 2 becomes WHICH. Study these other pairs of sentences and note how they are linked: 3. Consumers are supplied at higher voltages than domestic consumers. 4. These consumers use large quantities of energy. 38 ^ Consumers WHO USE LARGE QUANTITIES OF ENERGY are supplied at higher voltages than domestic consumers. 5. 33 kV lines are fed to intermediate substations. 6. In the intermediate substations the voltage is stepped down to 11 kV. ► 33 kV lines fed to intermediate substations WHERE THE VOLTAGE IS STEPPED DOWN TO 11 kV. III. READING COMPREHENSION CONDUCTORS, INSULATORS AND SEMICONDUCTORS If we connect a battery across a body, there is a movement of free electrons towards the positive end. This movement of electrons is an electric current. All materials can be classified into three groups according to how readily they permit an electric current to flow. These are : conductors , insulators and semiconductors. In the first category are substances which provide an easy path for an electric current. All metals are conductors, however some metals do not conduct well. Mangarin, for example, is a poor conductor. Copper is a good conductor, therefore it is widely used for cables. A non- metal which conducts well is carbon. Salt water is an example of a liquid conductor. A material which does not easily release electron is called an insulator. Rubber, nylon, porcelain and air are all insulators. There are no perfect insulators. All insulators will allow some flow of electrons, however this can usually be ignored because the flow they permit so small. Semiconductors are midway between conductors and insulators. Under certain conditions they allow a current to flow easily but under others they behave as insulators. Germanium and silicon are semiconductors. Mixtures of certain metallic oxides also act as semiconductors. These are known as thermistors. The resistance of thermistors falls rapidly as they temperature rises. They are therefore used in temperature - sensing devices. 39 IV. EXERCISES Exercise 1 Rephrasing Rewrite the following sentences, replacing the words in italics with expressions from the passage which have similar meaning 1. The flow of free electrons is an electric current. 2. Materials in the first group are called conductors. 3. Materials which provide a path for an electric current are conductors. 4. All insulators permit some flow of electrons. 5. Germanium sometimes acts as an insulator and sometimes as a conductor. Exercise 2 Contextual reference What do the pronouns in italics in these sentences refer to? 1. All materials can be classified into three groups according to how readily they permit an electric current to flow. a. three groups b. all materials c. free electrons 2. Under certain conditions they allow a current to flow easily but under others they behave as insulators. a. conductors b. semiconductors c. insulators 40 3. These are known as thermistors. a. metallic oxides b. semiconductors c. mixtures of certain metallic oxides 4. They are therefore used in temperature- sensing devices a. thermistors b. semiconductors c. metallic oxides Exercise 3 Checking facts and ideas Decide if these statements are true or false. Quote from the passage to upport your decisions. Correct the false statements 1. Electrons flow from positive to negative. 2. Copper provides an easy path for an electric current. 3. All metals are good conductors. 4. All good conductors are metals. 5. Air is not a perfect insulator. 6. Rubber readily releases electrons. 7. The resistance of a thermistor is higher at low temperatures than at high mperatures. 41 Exercise 4 Relative clause 1. Study these sentences : 1. Starter motor brushes are made of carbon 2. The carbon contains copper. Both these sentences refer to carbon. We can link them by making sentence 2 a relative clause. Example: ----------► Starter motor brushed are made of carbon WHICH CONTAINS COPPER. The relative clause is in capitals. Note that the carbon in sentence 2 becomes WHICH. Study these other pairs of sentences and note how they are linked: 3. Consumers are supplied at higher voltages than domestic consumers. 4. These consumers use large quantities of energy. Example: -------► Consumers WHO USE LARGE QUANTITIES OF ENERGY are supplied at higher voltages than domestic consumers. 5. 33 kV lines are fed to intermediate substations. 6. In the intermediate substations the voltage is stepped down to 11 kV. Example: -------► 33 kV lines fed to intermediate substations WHERE THE VOLTAGE IS STEPPED DOWN TO 11 kV. Now link these sentences. Make the second sentence in each pair a relative clause: 1. The coil is connected in series with a resistor. The resistor has a value of 240 ohms. 42 2. The supply is fed to a distribution substation. The supply is reduced to 415 V in the distribution substation 3. Workers require a high degree of illumination. The workers assemble very small precision instruments. 4. Manganin is a metal. This metal has a comparatively high resistance 5. The signal passes to the detector. The signal is rectified by the detector 6. A milliameter is an instrument. The instrument is used for measuring small current 7. Workers require illumination of 300 lux. The workers assemble heavy machinery. 8. Armoured cables are used in places. There is a risk of mechanical damage in these places. 43 Unit 5 ELECTRIC MATERIALS: SUPERCONDUCTORS (Vât liêu điên: Vât liêu siêu dẫn) I. VOCABULARY overheat : quá nóng dirt : bụi, bẩn gap : lỗ hổng, khe hở therefore : bởi vậy, vì th ế , cho nên comma : dấu phẩy alloys : hợp kim steadily : 1. vững, vững chắc; 2ệ đều đặn, đềuđều decrease : giảm bớt, làm suy giảm negligible : không đáng kể absolute : tuyệt đối, hoàn toàn; thuần tuý, nguyên chất propose : đề nghị; đề xuất, đua ra induce : l ế gây ra, đem lại; 2. (điện học) cảm circulate : lưu thông, luân chuyển , tuần hoàn theory : lý thuyết, lý luận, nguyên lý memory : l ề trí nhớ, ký ức; 2. (tin học) bộ nhớ máy tính. store : 1. tích trữ, để dành; 2. chứa, đựng, tích information : thông tin 44 indefinitely : vo han dinh, khong biet den bao gid retrieve : lay, goi ra (thong tin duoc luu tru) due to : vi, nhd co, do bdi, tai windings : 1. sir cuon, sir cuon; 2. (ky thuat) su venh occur : xuat hien ideal : quan niem, tu tuong Similarly : tuong tu, giong nhau efficient : co hieu luc, co hieu qua exhibit : trung bay, trien lam advantage : su thuan loi, hoan canh thuan loi, moi loi summarize : tom tat, tong ket summary : tom tat, tong ket soft iron : sat mem electromagnet : (vat ly) nam cham dien magnetize : tir hoa cover : bao phu care : chu y den, de y den solder : han capacitance : (dien hoc) dien dung microfarad : micro phara II. GRAMMAR Reason and result connectives 1. How to use because, because of and therefore Study these sentences : 1. Copper is used for cables. 2. Copper is a good conductor. 45 Sentence 1 tells us what copper is used for. Sentence 2 tells us why it is used . Sentence 2 provides a reason for sentence 1. We can link a statement and a reason using because. -------► 1+2 Copper is used for cables BECAUSE it is a good conductor. When the reason is a noun or a noun phrase, we use because of. Example The motor overheated because o f dirt in the air gap. Now study this pair: 3. The flow of electrons through an insulator is very small. 4. The flow can be ignored. Sentence 4 is the result of sentence 3. We can link a statement and the result using therefore. ------- ► 3 + 4 The flow of electrons through an insulator is very small, THEREFORE it can be ignored. Note that a comma is used before therefore. III. READING COMPREHENSION SUPERCONDUCTIVITY The resistance of metals varies with their temperature. When they get hot, their resistance increases. When they are cool, their resistance falls. The resistance of some metals and alloys steadily decreases as their temperature is lowered, then falls suddenly to a negligible value at temperatures a few degrees above absolute zero (- 273°C). In other words, these materials have almost no resistance to an electric current at very low temperatures. They become almost perfect conductors. This is called superconductivity. It occurs only with certain materials, for example lead, and only at very low temperatures. The practical applications of superconductivity are limited because of the very low temperatures required. A number of uses, however, have been 46 proposed. If a current is induced by a magnetic field in a ring of superconducting material, it will continue to circulate when the magnetic field is removed. In theory this could be made use of in the memory cells of computers. Memory cells made of superconducting materials could store information indefinitely. Because of zero resistively of the cells, the information could be retrieved very quickly, as fast as 10'x seconds. Ninety per cent of the total losses in modern transformers is due to the resistance of windings. Transformers could be made with windings cooled to the low temperature sat which superconductivity occurs. The resistance of the windings would be zero and the transformer would be almost ideal. Similarly a 100% efficient electric motor has been proposed using the magnetic field of superconducting coils. IV. EXERCISES Exercise 1 Answer the following questions: 1. Name a superconducting material. 2. When do materials exhibit superconductivity? 3. Why are the practical applications limited? 4. What applications have been proposed? 5. What advantages would a memory cell made of superconducting naterial have? 6. How efficient would transformers and motors be which used uperconductivity? 47 Exercise 2 Summarizing Complete this summary of the passage using your answers to exercise 1. 1. Some metals, for example.......................................... . become almost perfect conductors a t .................................. 2. The applications of superconductivity are limited because ....................... Possible uses a r e .................................... 3. A superconducting memory cell would allow inform ation..................... 4. A transformer or motor using superconductivity would be....................... Exercise 3. Reason and result connectives 1. Study these sentences : 1. Copper is used for cables. 2. Copper is a good conductor. Sentence 1 tells us what copper is used for. Sentence 2 tells us why it is used . Sentence 2 provides a reason for sentence 1. We can link a statement and a reason using because . ------- ► 1 + 2 Copper is used for cables BECAUSE it is a good conductor. When the reason is a noun or a noun phrase, we use because of. Example The motor overheated BECAUSE OF dirt in the air gap. Now study this pair: 3. The flow of electrons through an insulator is very small. 4. The flow can be ignored. Sentence 4 is the result of sentence 3. We can link a statement and the result using therefore. ► 3 + 4 The flow of electrons through an insulator is very small, THEREFORE it can be ignored. 48 Note that a comma is used before therefore. Now link these ideas using- because or therefore 1. Soft iron is used in electromagnets. Soft iron can be magnetized easily. 2. The voltage is 250 V and the current 5 A. The resistance is 50 Q 3. Pvc is used to cover cables Pvc is a good insulator. 4. Transistors can be damaged by heat. Care must be taken when soldering transistors. 5. Capacitance is usually measured in microfarads or picofarads. The farad is too large a unit. 6. Output transistors are mounted on a heat sink. Output transistors generate heat. 49 Unit 6 CIRCUIT ELEMENTS (Những phần tử mach điên) I. VOCABULARY potential : (vật lý) (thuộc) điện thế path : đuờng dẫn source : nguồn device : thiết bị control : điều khiển limit : giói hạn rheostat : (điện học) cái biến trỏ, hộp số interrupt : (điện học) ngắt describe : miêu tả function : chức năng fuse : cầu chì protect : bảo vệ emphasize : nhấn mạnh pattern : mẫu, khuôn mẫu purpose : mục đích, ý định element : 1. yếu tố, 2. nguyên tố; 3. (điện học) pin a load : tải a transmission system : hệ thống truyền 50 provide : cung cấp the electromotive force : lực điện động establish : thành lập, thiết lập the difference : sự khác nhau flow : chảy supply : cung cấp, tiếp tế convert : đổi, biến đổi for instance : ví dụ nhu section : 1. đoạn, khúc, phần; 2. mục (của tài liệu) chassis : khung gầm (ôtô, máy bay) conduct : (vật lý) dẫn regulate : điều chỉnh, sửa lại cho đúng flashlight : đèn pin comprise : gồm có, bao gồm slide : truợt compare : so sánh operate : hoạt động aboard : trên tàu, trên máy bay space : khoảng trống, không trung satellite : vệ tinh solar cells : tế bào năng luợng mặt trời relay : cái ngắt mạch, ro le actuate : thúc đẩy, kích thích ground : dất, mặt đất although : dẫu cho, mặc dù complex : phức tạp oscilloscope : (điện học) máy điện dao động, máy hiện sóng pronoun : đại từ a soldering iron : sắt hàn wire- clippers : kéo xén dây điện 51 Study Figure 1. In this simple flashlight circuit, the source comprises three 1.5 V cell in series. The load is a 0.3 W bulb. Part of the transmission system is the metal body of the flashlight, and the control is a sliding switch. control wires Transmission system FIGURE 2 Compare figure 2. The function of this circuit is to operate a television camera aboard a space satellite. Here the source is a battery of solar cells. A solar cell is an electric cell which converts sunlight into electrical energy. The load is the television camera. The transmission system is the connecting wires. The control is a relay actuated by transmissions from ground control. Although the function of this circuit is much more complex than that of the flashlight, it too consists of the four basic elements. IV. EXERCISES Exercise 1 Rephrasing Rewrite the following sentences, replacing the words in italics with expressions from the passage which have a similar meaning. 54 1. A lamp converts electrical energy into light. 2. The generator provides the circuit with electromotive force. 3. The metal frame of the oscilloscope is part of its transmission system. 4. The rheostat controls the current flow in the circuit. 5. A battery of solar cells supplies power to the circuit. Exercise 2 Contextual reference What do the pronouns in italics refer to? 1. Current moves from a point of high potential energy to one of low potential. a. current b. energy c. a point 2. For example, it may be a generator or a battery. a. the source b. a device c. electromotive force 3. It is often possible, however, for the metal frame of a unit to be one section of its transmission system. a. the metal fram e’s b. the unit’s c. the circuit’s 55 4. Although the function of this circuit is much more complex than that of the flashlight, it too consists of the four basic elements. a. this circuit b. the function c. flashlight Exercise 3 Checking facts and ideas Decide if these statements are true or false. Quote from 'the passage to support your decisions. Correct the false sentences. 1. A difference in potentials required before current can flow in a circuit. 2. A generator is a source of electromotive force. 3. Loads convert electric energy into light and heat. 4. Transmission systems must consist of wires. 5. A rheostat may be used as a control. 6. The load in the flashlight circuit is a bulb. 7. The source in the satellite circuit is a solar cell. 8. The current flow in the satellite circuit is generates by a relay. 9. The flashlight circuit differs basically from the satellite circuit. 56 Exercise 4 Describing function When we answer the question What does X do?, we describe the function of X. Example - What does the fuse do? - It protects a circuit. We can emphasize function by using this pattern: - The function of a fuse is to protect a circuit. Now identify these components. Explain the function of each component with the help of this list. a. adds capacitance to a circuit b. rectifiers a alternating currents c. adds resistance to a circuit d. measures very small currents e. breaks a circuit f. protects a circuit g. varies the current in a circuit h. transforms AC voltages i. receives RF signals j. selects a frequency 57 3. 11^ 3 7. / 9. Exercise 5 Describing purpose 4. 0 - 0 m A 8 . V 0. When we answer the question What is X for?, we describe the purpose of X. Example - What is an ammeter for ? - It is for measuring current. 58 Other ways we can describe the purposes of an ammeter are 1. It is used for measuring current 2. It is used to measure current 3. We measure current with an ammeter 4. We measure current using an ammeter Now describe the purposes of these instruments and tools using ary of the structures presented above 1. a voltmeter 2. a soldering iron 3. a milliammeter 4. an oscilloscope 5. a heat sink 6. wire- clippers 7. a megohmmeter 59 8. an ohmmeter 9. a signal generator 10. a battery charger. 60 Unit 7 THE DC MOTOR (Đông cơ môt chiểu) I. VOCABULARY design thiết kế, phác hoạ direct current (dc) dòng diện một chiều alternating current (ac). dòng điện xoay chiều armature l ắ (kỹ thuật) lõi, cốt lõi; 2. (điện học) phần ứng loops (điện học) cuộn, mạch core (kỹ thuật) lõi, nòng, ruột segment (toán học) hình viên phân, phần, mảng interaction sự ảnh huỏng đến nhau, sự tương tác spin làm quay tròn sentence building dựng câu, đặt câu protect bảo vệ, bảo hộ, che chở excessive l ặ quá mức, thừa; 2. quá thể, quá đáng breaker (điện học) cái ngắt điện, cái công tắc brush bar (điện học) cái chổi driving truyền, truyền động end giới hạn, đoạn cuối bearing (kỹ thuật) cái giá, cái trụ, cái đệm, cutxinê 61 hub trục bánh xe, moayo holder (kỹ thuật) mâm cặp, vòng kẹp commutator (điện học) cái đảo mạch, cái chuyển mạch pressure (điện học) ứng xuất spring lò so, nhíp xe pole (vật lý) cực (nam châm, ắc quy) bolt (kỹ thuật) bu lông terminal (điện học) cực, đầu (điểm nối trong mỗi mạch điện) shaft trục typical đặc thù đặc trưng fed to dẫn đến a means phuong tiện alternate xen kẽ, luân phiên form làm thành, tạo thành set up sắp đặt principle nguyên lý , nguyên tắc a force năng lượng reverse đảo, nghịch, ngược lại, trái lại necessary cần thiết punctuation phép chấm câu accurate chính xác repetitive lặp đi, lặp lại solenoid (điện học) sôlênoit (cuộn dây kim loại trở nên có từ tính khi có dòng điện chạy qua) latch chốt cửa, then cửa overcome l ế tìm cách vượt qua, 2. đánh bại, khắc phục tension (điện học) điện thế, thế hiệu, sức diện động remains đồ thừa, cái còn lại towards : về phía release : tha, thả, phóng thích apart : về một bên, qua một bên, riêng ra, xa ra fault : (điện học) sự rò, sự lạc reset : vặn lại, lắp lại. II. GRAMMAR Motor can be designed to run on direct (dc) or alternating current (ac). It contains an armature, which is a set of wire loops wound on a steel core. This consists of a number of copper segments insulated from one another. The interaction of the forces produced by the magnetic field of the rotor and the stator makes the rotor spin. Sen ten ce building Join the following groups of sentences to make the longer sentence Example: 1. Circuits can be protected from excessive current by a fuse. 2. Circuit can be protected from excessive current by a circuit breaker. --------- ►(1+2) Circuits can be protected from excessive current by a fuse or by a circuit breaker. m . READING COMPREHENSION THE DC MOTOR 63 An electric motor is a machine for converting electrical energy into mechanical energy. Motor can be designed to run on direct (DC) or alternating current (AC). The motor shown in Figure 1 is a dc motor. Its most important parts are the rotor, the stator and the brushgear. The rotor is the moving part. It contains an armature, which is a set of wire loops wound on a steel core. When current is fed to the armature, these winding s produce a magnetic field. The armature and core are mounted on a shaft which runs on bearings. It provides a means of transmitting power from the motor. The rotor also contains a commutator. This consists of a number of copper segments insulated from one another. The armature windings are connected to these segments. Carbon brushes are held in contact with the commutator by springs. These brushes allow current to pass to the armature windings. As the rotor turns , the commutator acts as a switch making the current in the armature alternate. The stator does not move. It consists of magnetic and electrical conductors. The magnetic circuit is made up of the frame and the pole. Wound round the poles are the field coils. These form the stator’s electrical circuit. When current is fed to them, a magnetic field is set up in the stator. The motor operates on the principle that when a current - carrying conductor is placed in a magnetic field, a force is produced on the conductor. The' interaction of the forces produced by the magnetic field of the rotor and the stator makes the rotor spin. tle c in c m oiot IV. EXERCISES Exercise 1 Meaning from context Select the word from the three alternative given which is most similar in meaning to the word in italics as it is used in the passage: 1. provide a. produces b. supplies c. allows 2. segments a. sections b. pieces c. wires 65 3. alternate a. reverse b.change c. flow in one direction then in another 4. interaction a. acting together b. operation c. result Exercise 2 Completing a diagram Complete the following diagram of the components of a dc motor using the information in the passage and Figure 1 Dc mo or brushgea spring core commutator magnetic conductors electrical conductors poles 66 Exercise 3 Describing position Describe where the following components are located using the information in the passage and Figure 1. Example: - Where are the armature windings? - They are on a steel core 1. the armature windings 2. the core 3. the fan 4. the field coils 5. the poles Exercise 4 Sentence building Join the following groups of sentences to make the longer sentences. Use the words printed in italics at the beginning of each group. You may omit words and whatever changes you think are necessary in the word order and punctuation of the sentences. 67 1. or Circuits can be protected from excessive current by a fuse. Circuit can be protected from excessive current by a circuit breaker. 2. however A fuse is the simplest and cheapest protection. For accurate and repetitive operation a circuit breaker is used. 3. which The simplest circuit breaker consists of a solenoid and a switch with contacts. The contacts are held closed by a latch. 4. which, therefore At normal currents the pull of the solenoid on the latch will not overcome the tension of the spring. The spring holds the latch in place. The switch remains closed. 5. if The current rises to a dangerous level. The pull of the solenoid on the latch increases. 68 6. and The increased pull overcomes the latch spring tension. The increased pull pulls the latch towards the solenoid. 7. which This releases the switch contacts. ' The switch contacts are pulled apart by a spring. 8. as The circuit is now broken. The unit is protected 9. when The fault in the supply or unit is put right. The latch can be reset. 69 ưnit 8 TESTING THE ELECTRIC MOTOR (Kiểm tra đông cơ điên) I. VOCABULARY : sự cung cấp : ngắt, cắt (dòng điện) : cầu trì : bộ khỏi động, tắc te đèn ống : ỏ vào cuối, chót tận cùng : mê ga oat : chì, tấm chì : khung động co : máy p h át, máy phát điện : làm quay, làm xoay quanh m inute): vòng trên phút : số ghi (trên đồng hồ điện) : cô lập, cách, cách ly, tách ra. : cuộn khải động : riêng , riêng lẻ, cá nhân : lỗi : chổi 70 supply disconnect fuse starter terminal megohmmeter lead motor frame generator rotate rpm (revolution per reading isolate starter coil individually fault brush lift off : phóng vụt lên commutator : cái chuyển mạch, cái đảo mạch field : trường, điện truờng winding : sự cuốn, sự cuộn gear : bánh răng, sự chuyển động satisfactory : vừa lòng, vừa ý, thỏa mãn armature : cốt lõi, phần ứng separately : riêng biệt locate : xác định vị trí, định vị flow : trôi nổi, chảy chart : đổ thị, biểu đồ fill : lấp đầy, đổ đầy missing : mất đi, bỏ quên preceeding : có trước range : vùng operate : hoạt động baterry : ắc quy device : thiết bị chemical energy : năng luợng hóa học rectifier : máy chỉnh lưu magnetic effect : tác động từ truờng receiver : máy thu, ống nghe headphone : tai nghe impedance : trỏ kháng plate : tấm, bản kim loại beam : tia, chùm act : hành động 71 II. GRAMMAR The supply should be disconnected by opening the main switch and removing the fuses. The megohmmeter generator should be rotated at about 60 rpm and a reading taken. I f the resistance is found to be low, then the starter should be isolated and the test repeated on the starter alone. //th e resistance is satisfactory, then the armature only should be tested. Relative clauses Clauses with prepositions Examples: 1. The resistor has a value of 33000 ohms 2. The capacitor is connected across the resistor. We can be linked using a relative clause: ------- ►The resistor ACROSS WHICH THE CAPACITOR IS CONNECTED has a value of 33000 ohms Preposition ‘across’ is must be included in the relative clause Writing impersonal instructions Study these instructions: 1. Use a high - resistance voltmeter. 2. Do not insert a fuse in an earth conductor. In writing, instructions are often made impersonal using should. Examples 1. A high - resistance voltmeter should be used. 2. A fuse should not be inserted in an earth conductor. We can emphasize an instruction by using must. 72 Examples 1. A high - resistan ce voltm eter m ust be used. 2. A fuse m u st not be inserted in an earth conductor. III. READING COMPREHENSION TESTING THE ELECTRIC MOTOR The supply should be disconnected by opening the main switch and removing the fuses. Both starter input terminals are joined together and connected to one terminal of the megohmmeter. The other lead of the megohmmeter is connected to the motor frame. The megohmmeter generator should be rotated at about 160 rpm and a reading taken. If the resistance is found to be low, then the starter should be isolated and the test repeated on the starter alone. If the resistance is still low, then the starter coil should be checked individually until the fault is located. If the resistance of the starter is high, then the fault must lie in the motor and not in the starter. The brushes should be lifted off the commutator and the field windings and brushgear tested. If the resistance is satisfactory, then the armature only should be tested. If the resistance is low, then the field windings and brushgear should be tested separately until the fault is located. This flow chart provides instructions for how to test a DC motor. Fill in the missing instructions with the help of the preceding description 73 Start 74 IV. EXERCISES Exercisel Relative clauses Clauses with prepositions Example: 1. The resistor has a value of 33000 ohms 2. The capacitor is connected across the resistor. We can be linked using a relative clause: -----►The resistor across which the capacitor is connected has a value of 33000 ohms Now link these sentences 1. The range is 0 - 1000 volts. The meter can operate over the range. 2. A baterry is a device. The device changes chemical energy into electrical energy. 3. Power suplies are used to drive DC motor The power suplies use thyristor rectifiers. 4. The capacitor has a value of 27 pF. 5. The telephone is a device. The device uses the magnetic effect of a current. 75 6. The receiver can only be used with headphones. The headphones have a high impedance. 7. The plates are known as X and Y plates. The beam passes between the plates. 8. The rotor contains a commutator. The commutator acts as a switch. Exercise 2 Writing impersonal instructions Study these instructions: 1. Use a high - resistance voltmeter. 2. Do not insert a fuse in an earth conductor. In writing, instructions are often made impersonal using should. Examples 3. A high - resistance voltmeter should be used. i 4. A fuse should not be inserted in an earth conductor. We can emphasize an instruction by using must. Examples 5. A high - resistance voltmeter must be used. 6. A fuse must not be inserted in an earth conductor. 76 Here are some points to remember when using transistors . Study them: 1. Use heat shunts when soldering. 2. Do not connect or disconnect transistors with the ppower on. 3. Do not use an ohmmeter for checking transistors unless a safe voltage or current range is used. 4. Keep sharp bends in the leads at least 1.5 mm away from the transistor body. 5. Do not exceed the reverse breakdown voltage. Rewrite each instruction to make it impersonal using should . Example: --------- ► The heat shunts should be used when soldering. Now you do the same: 1 2 ........................................................................................................... ........................................................................................................................3 ........ 4 ............................................................................................................ 5 .............................................................................................................. Then emphasize each instruction using must. Example ----------► The heat shunts must be used when soldering. Now you do the same: 1 ........................................................................................................................................................................................... 2 ................................................................................................................................................................ ....................................................................................................................3 .!.......... 4 5 77 Unit 9 TRANSFORMERS (May bien ap) I. VOCABULARY : quan (quanh) dien the bien do vdng, quay, xoay tang giam khuc quanh, 1 vong quay minh hoa su hien dien, sir co mat that su, thirc su tuong tu co ban la manh, iMu, vien, khuc, cuc trang bi cuong do, am luong so cap dau vao 78 wound voltage amplitude turn increase decrease winding illustrate presence virtually similar basically piece equipment magnitude primary input secondary output obtain insulate former mount sheet lamination oxidize so that reduce eddy loss centre limb own description diagram items component possible draw a carbon resistor variable filament bulb choke : thii cap : dau ra : dat duoc, gianh duoc, thu duoc : co lap, cach ly : cai trudc, van de truoc : dat, sap dat, dong vao : la, tam, phien, t6 : su can mong, su dat mong : bi gi set, o xi hoa : de, de cho, dang : giam, giam bot, ha : lam xoay loc : su mat, su thua, su that bai : trung tam : bo, ria : cua chinh minh, cua rieng minh : mieu ta : so do : khoan. mon, tin tuc : thanh phan, phan hop thanh : co the : ve : dien tro cac bon : co the thay doi duoc, co the thay bien doi duoc : bong den co day toe : (dien hoc) cuon cam khang 79 II. GRAMMAR A transformer basically consists o f two coils wound on a single iron core. A transformer may be used either to increase or descrease an applied voltage or to increase or descrease a current. Describing component The following verbs can be used to break down a piece of equipment into its component parts. Note how they are used: Consists of . D 80 X Comprises \ is composed of X and Y is made up of A contains C and D Incluses III. READING COMPREHENSION TRANSFORMER A transformer is a device which changes the magnitude of an ac voltage. The transformer consists of a primary coil to which the input is applies, and a secondary coil from which the output is obtained. The coils are insulated and wound round a former. The coils have a core of soft iron on which the former is mounted. The core is made from many thin sheets or laminations. The sheets are oxidized so that the sheets are insulated from each other. Oxidizing the sheets reduces eddy losses. 3 4 IV. EXERCISES Exercise 1 Describing component The following verbs can be used to break down a piece of equipment into its component parts. Note how they are used: 81