MỘT SỐ CÂU HỎI THAM KHẢO MÔN AVCN2

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MỘT SỐ CÂU HỎI THAM KHẢO MÔN AVCN2 Câu 1: A variable capacitor is used to vary capacitance in a circuit. Câu 2: The movement of the spot across the screen is controlled by the line scan signal. Câu 3:An aerial is used to receive RF signals. Câu 4: Parallel wires is the simplest type of transmission line consisting of a pair of insulated copper wire running side-by-side and covered by a plastic sheath. Câu 5: The term ATV, Advanced (nâng cao) Television, is used in USA Câu 6: A transformer is used to step AC voltage up or down. Câu 7: The playing mechanism of CDs is optical Câu 8: Radiophones, using the VHF band, were developed (phát triển)during the Second World War to provide communications for ships (tàu) and aeroplanes (máy bay). Câu 9:A fuse is used to protect (bảo vệ) a circuit. Câu 10: The term HDTV is used in Europe Câu 11: The optimal (tối ưu) viewing distance (khoảng cách) for HDTV is three times the height of the screen compared (so sánh) with seven times the present (hiện nay) televisions. Câu 12: A variable resistor is used to vary the current in a circuit. Câu 13: Cells change chemical energy into electricity. Câu 14: EMF is abbreviation of electromotive force Câu 15: Primary cells is a type of cells, which cannot be recharged. Câu 16: Secondary cells is a type of cells, which can be recharged. Câu 17: 7 is the best number of cells to form a cluster (cụm). Câu 18: In a digital watch, a divider divides the frequency 15 times. Câu 19: In a digital watch, a LCD displays the times. Câu 20: Existing (hiện tại) European television pictures are made up of 625 lines, in comparison (so sánh) an HD picture consists of 1250 lines. Câu 21: For HDTV, the width/height of the screen is 16:9, like the screens in cinemas. Câu 22: See figure below. Which type of transmission does the figure describe? Optical fibres Câu 23: The frame must be scanned at least forty times per second to prevent (ngăn chặn) the screen from flickering.(nhấp nháy) Câu 24: Optical fibres is a kind (loại) of transmission line cables, in which non-visible light from lasers or LED can travel along the fibre by reflection from the surface (bề mặt). Câu 25: When recording a CD, sound is samplied (lấy mẫu) 44,100 times every second. Câu 26: A bridge circuit is used to converts alternating current to produce direct current. (Một mạch cầu sử dụng để chuyển đổi dòng điện xoay chiều ra dòng điện 1 chiều) Câu 27: You can record sound on tape or disc. Câu 28: A DAC converts digital signals into analogue signals. Câu 29: Existing European television pictures are made up of 625 lines, in comparison an HD picture consists of 1250 lines. Tiếp: ∼ 100 µm clad din g cor e light reflecte d at core/cla dding interfac e 1 Câu 1: Multimeters can have analogue or digital displays and can be switched (chuyển) to different measuring rages (Phạm vi thang đo). Câu 2: A variable capacitor is used to vary capacitance in a circuit. Câu 3: The movement (chuyển động) of the spot across the screen is controlled by the line scan signal. Câu 4: Which of the sections (bộ phận) is the main section of a cathode ray tube (CRT)?  Electron gun ; Diflection system ; Phosphor screen. Câu 6: An aerial is used to receive RF signals. Câu 7: What do we call equipment for scanning the human body for disease? A electronic stethoscopes Câu 8: What controls the movement of the spot of light down a television screen? The line scan signal Câu 10: Function generator (bộ phát sóng) is an instrument which can be used to test and adjust a variety of electronic equipment such as audio amplifiers(1 loạt các thiết bị điên tử) Câu 11: Mains frequency interference results in hum. Câu 12: In fax machine, the thermal head is a mechanism containing a line of dots which heat up or cool down depending (phụ thuộc)on the electrical current supplied (xung dòng điện)to them by the binary code. Câu 13: Parallel wires is the simplest type of transmission line consisting of a pair of sinsulated copper wire running side-by-side and covered by a plastic sheath. Câu 14: They are used to control different functions of digital watches such as hour display, date and alarm signal. What are they?  The fulses Câu 15: The term ATV, Advanced Television, is used in USA Câu 16: Which of the instruments would you use to determine (xác định ) the value of the current through a transformer?  Multimeters Câu 17: What controls the movement of the spot of light across a television screen?  The line scan signal Câu 18: The invention of the telephone enabled speech to be transported as electrical signals along wires and revolutionized personal communications Câu 19: Type of zinc-carbon cells is primary Câu 20: Noise generated within components causes hiss Câu 22: A piece of transparent (trong suốt) plastic, known as a graticule (lưới địa lý) is attached (gắn)to the front of the screen.(mặt trước của màn hình) Câu 23: Oscilloscopes use changed metal plates to give an electrostatic deflection (dò bằng tĩnh mạch) Câu 24: A transformer is used to step AC voltage up or down. Câu 25: The positive electrode of zinc-carbon cells is made of manganese dioxide Câu 26: Overheating a transistor is due to damage. Câu 27: A current is driven through the battery in the opposite direction to (hướng ngược lại) its normal output current. Câu 28: Recording system of CDs is digital Câu 29: In mobile networks, all the base stations for a cluster of cells are permanently connected to a main switching centre (MSC) Câu 30: In the HDTV system, their wide frequency ranges make it possible to transmit (phát) digital, rather than analog signals. 2 Câu 31: The aim (mục đích) of high definition television (HDTV) is provide the viewer with more realistic images (h.a trung thực)than are offered by today’s television set. Câu 32: Logic probe is an instrument which can be used to measuring voltage levels and pulses. Câu 33: What happens to a screen if the frame is not scanned at least forty times per second?  flickering Câu 34: A build-up of oxide on the head causes the tape rubbing (cọ sát) againts the head. Câu 35: The playing mechanism of CDs is . a. chemical b. electrical c. mechanical d. optical Câu 36: A digital recording system, known as a compact disc system, was introduced in 1982 Câu 37: Type of NiCad cells is secondary Câu 38: Electromotive force means EMF Câu 39: The negative electrode of zinc-carbon cells is made of zinc Câu 41: Which of the instruments would you use to measure the frequency of an oscillator?  oscilloscope Câu 43: Sound quality of CDs like the original (như bản gốc) Câu 44: Dust on records causes crakle Câu 45: The video signal contains line and field sync pulses to make sure that the TV receiver starts a new line and a new frame at the same times as the TV camera. Câu 46: In oscilloscopes, the electron beam hits the screen, making the phosphor glow and causing a spot to be displayed. Câu 47: Early reel-to-reel machines used one-inch wide tape and made the most of the available band width by moving the tape past the head at high speed. Câu 48: If the oscilloscope has an astigmatism control, it is used to vary the voltage on the third anode. Câu 51: The frame must be scanned at least forty times per second to prevent the screen from flickering Câu 52: What name is given to the rapid movement of the spot back to across the screen to the start of the next line?  the term ‘ flyback ’ Câu 53: The frequency which is created from quartz crystal is halved 15 times by a microchip resulting in a frequency of one pulse per second. Câu 54: Recording system of LPs is an nalogue Câu 55: Which of the instruments would you use to test for the presence of a control signal on the output pin of a computer chip?  logic probe Câu 57: If the doors are fitted with a time-delay mechanism, they remain open for about four seconds before closing again. Câu 58: The electrolyte of zinc-carbon cells is a solution of ammonium chloride Câu 59: Although the optical fibre has a smaller diameter than a human hair, it can be used to transmit ten of thousands of signals at high speed with very low loss and no interference from other signals. Câu 60: Radiophones, using the VHF band, were developed during the Second World War to provide communications for ships and aeroplanes. Câu 61: A fuse is used to protect a circuit. Câu 62: The term HDTV is used in Europe 3 Câu 63: The first true telecommunications systems using electrical signal to carry (mang) messages started in 1840s with machine telegraphy. Câu 64: By spinning the head at a high speed, the rate (tỷ lệ) at which the data could be stored or retrieved was increased (tăng lên) Câu 65: The optimal viewing distance for HDTV is three times the height of the screen compared with seven times the present televisions. Câu 66: A variable resistor is used to vary the current in a circuit. Câu 68: Mains frequency interference results in hum Câu 69: Early VCRs were playback –only, but by building in a full-colour TV tuner, programmes could be recorded from the air while another channel was being viewed on a normal TV. Câu 70: The lastest machines, which must be linked to a special digital phone line, can send a document to several places at once for the price (chi phí) of one phone call. Câu 71: The divider circuits in an electronics of digital watch perform binary division on the pulses to reduce (giảm) frequency to one pulse per second. Câu 72: The power to drive an electronic circuit is normally provided by an AC mains power supply. Câu 73: A diode is used to rectify alternating current. Câu 74: Type of zinc-carbon cells is primary Câu 75: When the electron beam reaches the right side of the screen, it rapidly returns to the left side again. Câu 76: Aligning (sắp xếp) the head at an angle to the tape laid down the information as a series of started tracks. Câu 77: On most VCRs audio information is transferred via a static audio head which puts information on a separate track from the video signal. Câu 81: Poor recordings causes dirty heads Câu 82: The movement across the screen is controlled by the line scan signal while the movement down the screen is controlled by the field scan signal. Câu 83: In mobile networks, the MSC keeps a register of cellphones indicating the cell position Câu 84: When the probe is placed on the pin of a logic IC, small colour LEDs light up to indicate if a pulse is directed or whether the pin is at a high or a low logic level.  Ngữ pháp : • Sử dụng causing - making VD: The electron beam hits the screen causing the phosphor to glow. The electron beam hits the screen making the phosphor glow. The phosphor glows causing a spot to be displayed 1. A magnetic field is set up in the speaker coil making the coil vibrate(dao động). A magnetic field is set up in the speaker coil causing the coil to vibrate 2. The coil pushes and pulls the speaker cone causing sound waves to be produced. 3. A voltage is applied to a quartz crystal making it expand and contract. A voltage is applied to a quartz crystal causing it to expand and contract. 4. A voltage is applied to the Y-plates causing the electron beam to be deflected. 5. Current flows through the filament making the heater glow. Current flows through the filament causing the heater to glow. • Sử dụng meant that & As a result of 4 VD: Spinning the head at a high speed meant that the rate at which the data could be stored or retrieved was increased. As a result of spinning the head at a high speed, the rate at which the data could be stored or retrieved was increased. 1. Improvements in magnetic tape and the use of helical scanning meant that far more data could be crammed into a smaller area. As a result of Improvements in magnetic tape and the use of helical scanning , far more data could be crammed into a smaller area. 2. Như VD 3. Aligning the head at an angle to the tape meant that the information was laid down as a series of slanted tracks. As a result of aligning the head at an angle to the tape , the information was laid down as a series of slanted tracks. 4. Recording information in slanted tracks meant that the cassette tape could be narrower and the tape could move at a slower speed. As a result of recording information in slanted tracks , the cassette tape could be narrower and the tape could move at a slower speed 5. All these improvements meant that the modern VCR could be produced. As a results of all these improvements , the modern VCR could be produced. 6. The inclusion of a timer meant that recordings could be made and viewed at a later date. 7. As a results of the inclusion of a timer ,recordings could be made and viewed at a later date. • Ghép câu: 1. A television picture is built up gradually by a moving spot. 2. The spot strikes the television screen making the phosphor coating on the screen emits light which varies in brightness according to the intensity of the original image. 3. When the spot reaches the right side of the screen, it is blanked and moved rapidly back to the left side in a movement called flyback. 4. The present European system sweeps the screen in 625 closely-spaced lines to ensures a good quality picture. 5. While the movement across the screen is controlled by the line scan signal, it down the screen is controlled by the field scan signal. 6. If the scan rate must be greater than 40Hz, the screen will be flickering. 7. Sync pulses are added to the video signal which to ensure that the TV camera and TV receiver start a new line and frame at the same time. 8. The build-up of the screen happens so quickly that the eye sees only a complete picture. • Điền từ vào vào bài khóa : Bài 1: Cathode ray tube 5 Televisions as well as computers, radar systems, and oscilloscopes use a cathode ray tube (CRT) to produce an output display. The construction and operation of the CRT is similar in each case but the simplest type of CRT is found in oscilloscopes. A CRT is really a large vacuum tube valve. It has three main sections. The first section is an electron gun which emits a stream of electrons. The electron gun contains an electron lens which focuse the electrons into a narrow electron beam . The second section is a deflection system, which allows the beam to be moved vertically or horizontally. Oscilloscopes use charged metal plate to give electromagnetic deflection, whereas television sets use electromagnetic coils to give electromagnetic deflection The last section is a screen with a phosphor coating. The electron beam hits the screen, making the phosphor glow and causing a spot to be displayed. The colour of the spot depends on the type of phosphor used. Bài 2: Chia động từ trong ngoặc. Alexander Graham Bell invented the telephone in 1878. He is a Canadian whose family came from Scotland. Since then, telephone systems have grown dramatically; in the UK alone there is now over 24 million lines. Formerly, the UK system has been analogue. Many changes have taken place in recent years. Almost the entire UK network is now digital. Fibre optic cables replace the old copper lines. Previously, telephone exchanges have been used banks of electromagnetic relays for switching. Today, they have computer-controlled units. The new network is fast and reliable, allowing users access to many other communications services. Bài 3: Chia động từ trong ngoặc. Many changes have taken place in telephone design in recent years. Formerly, telephones have had rotary dials. A pulse has signaled each dialled number. Now, push- buttons replace dials. Each button triggers a different audio-frequency tone. This is know as multi-frequency dialling. Also, the handset is changed. Old models contain carbon microphones, which are inexpensive and robust but noisy. Today, moving-coil and electret devices to replace the old microphones. Advances in technology allow additional features to be added to phones. Most now are contained memories to store frequently-used numbers. Some telephone manufacturers add LCDs which display dialled numbers and indicate the duration of calls. • Chức năng của 1 số : Divider  divides the frequency 15 times Decoder  produces s ignals to operate the LCD LCD  displays the time Oscillator  produces fixed frequency pulses Counter makes a binary count of the pulses Transmission lines Telecommunications involves the transmission of information, including voice, data, TV, and radio over long distances. The transmission medium can be free space (ground, 6 space, and sky waves), or the information can be guided between transmitters and receivers using transmission line cables of various kinds. These include: Viễn thông liên quan đến việc truyền tải thông tin, bao gồm thoại, dữ liệu, truyền hình và đài phát thanh trên một khoảng cách dài. Các phương tiện truyền dẫn có thể được miễn phí không gian (sóng mặt đất, không gian, và bầu trời), hoặc thông tin có thể được hướng dẫn giữa các thiết bị phát, thu sử dụng cáp đường dây truyền tải các loại.những Parallel wires This is the simplest type of transmission line consisting of a pair of insulated copper wires running side-by-side and covered by a plastic sheath (see Fig. ‘1). It is prone to interference and is only used to carry information over small distances such as telephone connections within a building. Đây là loại đơn giản của đường dây truyền tải bao gồm một cặp dây đồng cách điện chạy side-by-side và được bao phủ bởi một vỏ bọc nhựa (xem hình. "1). Nó là dễ bị can thiệp và chỉ được sử dụng để truyền thông tin trên một khoảng cách nhỏ như kết nối điện thoại trong một tòa nhà. Twisted pair (cáp xoắn) Two insulated copper wires are twisted together to reduce interference effects and are enclosed in an insulating polyethylene sheath (see Fig. 2). Because the wires are twisted, unwanted stray signals picked up by one tend to be cancelled by similar signals picked up by the other. They are used for communications over longer distances, for example to connect telephones to their local exchange. Hai dây đồng cách điện được xoắn lại với nhau để giảm hiệu ứng giao thoa và được kèm theo trong một vỏ bọc cách điện polyethylene (xem hình 2). Bởi vì các dây xoắn, tín hiệu không mong muốn đi lạc được bởi một trong những xu hướng bị hủy bỏ bởi các tín hiệu tương tự chọn khác. Chúng được sử dụng cho thông tin liên lạc trên một khoảng cách dài hơn, ví dụ như để kết nối điện thoại để trao đổi địa phương của họ. Coaxial cable (coax) (cáp đồng trục) Flexible coax has a copper wire core surrounded by copper braid. The core and braid are insulated from each other by a dielectric material such as polyethylene and covered by a PVC sheath (see Fig. 3). 7 The braid helps to screen the signals from interference. Coax can carry a large number of signals over long distances at frequencies up to 1 000MHz. It is used to connect telephone exchanges and for cable television. Linh hoạt dỗ có một lõi dây đồng được bao quanh bởi braid đồng. Cốt lõi và bím tóc được cách điện với nhau bởi một chất điện môi như polyethylene và được bao phủ bởi một vỏ bọc PVC (xem hình 3). Braid giúp sàng lọc các tín hiệu từ sự can thiệp. Dỗ có thể thực hiện một số lượng lớn các tín hiệu trong khoảng cách dài ở tần số lên tới 1 000MHz. Nó được sử dụng để kết nối trao đổi điện thoại và truyền hình cáp. Waveguides ( dẫn sóng) Microwaves can be guided along rectangular copper ducts by a series of reflections from the inner walls (see Fig. 4). The exact dimensions of the ducts are determined by the frequency to be transmitted. Suitable frequencies are between 1GHz and 300GHz. Waveguides are used to carry microwave signals between dish aerials and receivers. vi sóng có thể được hướng dẫn dọc theo ống dẫn bằng đồng hình chữ nhật bằng một loạt các phản xạ từ các bức tường bên trong (xem hình 4). Các kích thước chính xác của các ống dẫn được xác định bởi tần số được truyền. Tần số phù hợp giữa bộ xử lý 1GHz và 300GHz. Ống dẫn sóng được sử dụng để thực hiện các tín hiệu vi sóng giữa các dây ăngten món ăn, thu. Optical fibres (cáp quang) An inner core made from very pure silica fibre is surrounded by a similar glass sheath, known as cladding. This is covered by a protective plastic sheath. Non-visible light from lasers or LEDs can travel along the fibre by reflection from the surface where the core and cladding meet (see Fig. 5). Although the optical fibre has a smaller diameterthan a human hair, it can be used to transmit tens of thousands of signals at high speed with very low loss and no interference from other signals. Optical fibre cable can be used in corrosive environments and is light, flexible and cheap. This type of cable is gradually replacing conventional copper wire for connecting telephones and computer networks. Một lõi bên trong được làm từ sợi silicon rất tinh khiết, được bao quanh bởi một vỏ bọc kính tương tự, được gọi là lớp phủ. Điều này được bao phủ bởi một lớp vỏ nhựa bảo vệ. 8 Không nhìn thấy được ánh sáng từ tia laser hoặc đèn LED có thể đi du lịch dọc theo sợi bởi sự phản xạ từ bề mặt cốt lõi và lớp phủ đáp ứng (xem hình 5). Mặc dù sợi quang học có một diameterthan nhỏ hơn một sợi tóc của con người, nó có thể được sử dụng để truyền hàng chục ngàn các tín hiệu ở tốc độ cao với sự mất mát rất thấp và không có sự can thiệp từ các tín hiệu khác. Cáp sợi quang có thể được sử dụng trong môi trường ăn mòn và ánh sáng, linh hoạt và giá rẻ. Đây là loại cáp đang dần thay thế dây đồng thông thường để kết nối điện thoại và mạng máy tính. Multimeter This instrument can be used to measure a number of different electrical quantities, such as voltage, current, and resistance, i.e. it is a combined voltmeter, ammeter, and ohmmeter. Multimeters can have analogue or digital displays and can be switched to different measuring ranges. Dụng cụ này có thể được sử dụng để đo một số số lượng điện khác nhau, chẳng hạn như điện áp, dòng điện, và giá trị điện trở, vân vân. nó kết hợp một vôn kế, ampe kế, và Ôm kế. Đồng hồ vạn năng có thể hiển thị tín hiệu tương tự hoặc số và có thể được chuyển sang các thang đo khác nhau. Logic probe This instrument is used for measuring voltage levels and pulses in digital logic circuits. When the probe is placed on the pin of a logic IC, small coloured LEDs light up to indicate if a pulse is detected or whether the pin is at a high or a low logic level. Dụng cụ này được sử dụng cho đo mức điện áp và xung trong các mạch số. Khi đầu dò được đặt trên chân của một vi mạch lôgic, một đèn led nhỏ sáng lên cho biết nếu một xung được phát hiện hoặc chân của mạch logic ở mức cao hoặc mức thấp. Oscilloscope This instrument is used to measure fast-moving signals. It shows how a signal varies with time or relative to another signal. It uses a cathode ray tube to display the waveform of the measured signal on a screen. Dụng cụ này được sử dụng để đo tín hiệu dịch chuyển. Nó cho thấy một tín hiệu thay đổi theo thời gian hoặc liên quan đến tín hiệu khác. Nó sử dụng một ống tia âm cực để hiển thị dạng sóng của tín hiệu đo trên màn hình. Function generator(bộ phát sóng) 9 This instrument contains a triangular wave oscillator which can be switched to produce triangular, square, or sine waves over a range of frequencies. It is used to test and adjust a variety of electronic equipment such as audio amplifiers. The function generator provides a known signal which can be injected into a circuit. Often it is used with an oscilloscope so that a visual display of the waveform can be seen. Thiết bị này bao gồm một sóng tam giác cái mà có thể được chuyển sang tạo ra các sóng tam giác, sóng vuông, hoặc sóng sin trên một phạm vi tần số. Nó được sử dụng để kiểm tra và điều chỉnh một loạt các thiết bị điện tử như bộ khuếch đại âm thanh. Chức năng cung cấp một tín hiệu được biết đến có thể được thêm vào mạch. Thường thì nó được sử dụng với một máy hiện sóng để hiển thị hình ảnh dạng sóng có thể được nhìn thấy. 10 . phosphor glow and causing a spot to be displayed. Câu 47: Early reel-to-reel machines used one-inch wide tape and made the most of the available band width by. dialled number. Now, push- buttons replace dials. Each button triggers a different audio-frequency tone. This is know as multi-frequency dialling. Also,