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1、Unit 2,Resistor, Capacitor and Inductor,第2/64页,Resistor，Capacitor and Inductor,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,第3/64页,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,第4/64页,If a battery is connected ac
2、ross a conducting material，a certain amount of current will flow through the material. This current is dependent on the voltage of the battery, on the dimensions of the sample, and on the conductivity of the material itself.1 The opposition to current is called electrical resistance and is represent
3、ed by the letter symbol R. The unit of resistance is the ohm, a term that is often expressed by using .One ohm is defined as that amount of resistance that will limit the current in a conductor is one ampere when the voltage applied to the conductor,Unit 2 Resistor, Capacitor and Inductor,Resistors,
4、Resistor, Capacitor and Inductor,电阻 假若将电池连接在导电材料上，一定数量的电流将流过此材料，流过材料的电流取决于电池的电压、材料的截面积和材料自身的电阻率。对电流的阻力叫电阻，用字母符号R表示。电阻的单位是欧姆通常用表示。l欧姆的定义为：当加到导体上的电压为l伏特时，将导体中的电流限制在1安培所需要的电阻值。,第5/64页,is one volt. Larger amounts of resistance are commonly expressed in kiloohm (K) and in megohm (M). The resistors are ma
5、de from carbon mixtures, metal films, or resistance wire and have two connecting wires attached. Variable resistors, with an adjustable sliding contact arm, are often used to control volume on radios and television sets.,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,较大的电阻值
6、常用千欧(K)和百万欧姆(M)表示。 电阻可以由碳混合物、金属薄膜或电阻丝制成，它有两个连线接头。常常用带有滑动臂的可变电阻器来控制收音机和电视机的音量。,第6/64页,Electrical energy can be stored in an electric field. The device capable of doing this is called a capacitor or a condenser. Capacitors consist of two metal plates that are separated by all insulating material.2 If
7、a battery is connected to both plates, an electric charge will flow for a short time and accumulate on each plate. If the battery is disconnected，the capacitor retains the charge and the voltage associated with it.3,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,Capacitors,
8、电容器 电能可以储存在电场中，能够储存电能的装置叫电容器。电容器是由被绝缘材料分开的两个金属板组成。如果电池被连接在两个金属板上，电荷将经过很短的流动而汇集在一个电极板上。假若断开电池，电容器将保持电荷以及与电荷相关的电压。,第7/64页,The ability of a capacitor to store electrical energy is termed capacitance. The capacitance is directly proportional to the dielectric constant of the material and to the area of
9、the plates and inversely to the distance of the plates.4 It is measured in farads .When a changer of one volt per second across it causes the current of one ampere to flow, the condenser is said to have the capacitance of one farad. However, farad is too large a unit to be used in radio calculation,
10、 so microfarad(10-6farads) and the picofarad (10-12farads) are generally used.,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,电容器储存电能的能力叫电容。电容器的电容量与介质的介电常数及平板的面积成正比，与平板间的距离成反比，其大小用法拉表示。当电容器两端的电压以每秒1伏的速率变化，产生的电流为1安培，就称电容器的电容量为1法拉。在无线电方面的计算中，法拉的单位太大，因此常用微法(法拉)和皮法(法拉)。,第8/64页,
11、lnductors consist of a conducting wire wound into the form of a coil. When a current passes through the coil, a magnetic field is set up around it that tends to oppose rapid changes in current intensity.5 All coils have inductance A coil of many turns will have more inductance than one of few turns.
12、 Also if a coil is placed on an iron core its inductance will be greater than it was without the magnetic core. The unit of induct-,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,Inductor,电感 电感是由绕成线圈形状的导线组成。当电流通过线圈时，在线圈周围将产生磁场，它将阻止电流的快速变化。一切线圈，都有电感。 匝数多的线圈比匝数少的线圈电感更大。而且，假若线
13、圈中放一个铁芯它的电感将比没有铁芯的线圈的电感更大。,第9/64页,ance The unit of inductance is the henry. A coil has an inductance of one henry if an induced emf of one volt is induced in the coil when the current through it changes at the rate of one ampere par second.6 Values of inductance used in radio equipment vary over a w
14、ide range.,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,电感的单位是亨利。当流过线圈的电流以每秒1安培的速度变化时，如果线圈中感应出1伏特感应电动势，那么，线圈的电感就是1亨利。用于无线电设备的电感值的变化范围很大。,第10/64页,Unit 2 Resistor, Capacitor and Inductor,Resistor, Capacitor and Inductor,New Words and Phrases,capacitor kpsit n. 电容器 capacitan
15、ce kpsitns n. 电容；电流容量 inductor indkt n. 授职者；感应器 inductance indktns n. 感应系数；自感应；电感 dimension dimenn, dai- n. 维；尺寸；vt. 标出尺寸adj. 规格的 conductivity ,kndktiviti n. 传导性；导电性；传导率 opposition ,pzin n. 反对；敌对；相反；反对派 carbon ka:bn n. 碳；碳棒；复写纸 adj. 碳的；碳处理的 film film n. 胶卷；薄膜；轻烟；膜层vi. 生薄膜； volume vlju:m n. 体积；卷；册；音量
16、；大量；adj. 大量的,第11/64页,wire wai n. 金属丝；电线；电报 vt. 拍电报；给装电线 condenser kndens n.冷凝器；压缩器；聚合器；电容器 proportional prup:nl adj. 成比例的；相称的，n. 比例项 insulate insjuleit vt. 隔离，使孤立；物使绝缘，使隔热 insulating adj. 绝缘的；隔热的（insulate的ing形式） accumulate kju:mjuleit vi. 累积；积聚 vt. 积攒 disconnect ,disknekt vt. 拆开，使分离 vi. 断开 retain ritein vt. 保持；雇；记住 dielectric ,daiilektrik adj. 非传导性的；诱电性的 n. 电介质；绝缘体 inversely inv:sli adv. 倒转地；相反地；反
