P1U1A(Electrical Networks)

翻译：归纳式(1-1A-1)、(1-1A-2) 和 (1-1A-4)描述的三种无源电路元 件如图1-1A-1所示。注意，图中电流的参考方向为惯用的参考方向，因 此流过每一个元件的电流与电压降的方向一致。
Active electrical devices involve the conversion of energy to electrical form. For example, the electrical energy in a battery is derived from its stored chemical energy. The electrical energy of a generator is a result of the mechanical energy of the rotating armature.
accumulate [ə'kju:mjuleit] vt.& vi.堆积，积累，增加
multiply vt.& vi.乘；（使）增加； （使）繁殖 substitute ['sʌbstitju:t] vt.& vi.代替，替换，代用 recall [ri'kɔ:l] vt.叫回，召回； 使想起，回想
翻译：纯电感电压由法拉第定律定义，法拉第定律指出：电感两端的电 压正比于流过电感的电流随时间的变化率。
The voltage developed across a capacitor is proportional to the electric charge q accumulating on the plates of the capacitor. Since the accumulation of charge may be expressed as the summation, or integral, of the charge increments dq, we have the equation
4.课文翻译讲解
过去分词短 语表示被动 An electrical circuit or network is composed语态 of elements such as resistors, inductors, and capacitors connected together in some manner. If the network contains no energy sources, such as batteries or electrical generators, it is known as a passive network. On the other hand, if one or more energy sources are present, the That引导同 resultant combination is an active network. In studying the 位语从句 behavior of an electrical network, we are interested in determining the voltages and currents that exist within the circuit. Since a network is composed of passive circuit elements, we must first define the electrical characteristics of these elements.
翻译：电路或电网络由以某种方式连接的电阻器、电感器和电容器等元 件组成。如果网络不包含能源，如电池或发电机，那么就被称作无源网 络。换句话说，如果存在一个或多个能源，那么组合的结果为有源网络。 在研究电网络的特性时，我们感兴趣的是确定电路中的电压和电流。因 为网络由无源电路元件组成，所以必须首先定义这些元件的电特性.
翻译：式中电容量C是与电压和电荷相关的比例常数。由定义可知，电流 等于电荷随时间的变化率，可表示为i = dq/dt。因此电荷增量dq 等电 流乘以相应的时间增量，或dq = i dt，
A summary of Eqs (1-1A-1), (1-1A-2) ,(1-1A-4) for the three forms of passive circuit elements is given in Fig. 1-1A-1. Note that conventional current flow is used, hence the current in each element is shown in the direction of decreasing voltage.
character: n.(人的)品质 passive['pæsiv] network 无源网络 性格；（事物的）性质， 特性
characteristic [,kærəktə‘ristik] adj. 特性(的)；n. 特性曲线， 特征，特色 Ohm [əum] n. 欧姆 Faraday ['færədi] n. 法拉第
翻译：就电阻来说，电压-电流的关系由欧姆定律给出，欧姆定律指出： 电阻两端的电压等于电阻上流过的电流乘以电阻值。
The voltage across a pure inductor is defined by Faraday’s law, which states that the voltage across the inductor is proportional to the rate of change with time of the current through the inductor.
翻译：电容两端建立的电压正比于电容两极板上积累的电荷q 。因为电 荷的积累可表示为电荷增量dq的和或积分，因此得到的等式为
Where the capacitance C is the proportionality constant relating voltage and charge. By definition, current equals the rate of change of charge with time and is expressed as i=dq/dt. Thus an increment of charge dq is equal to the current multiplied by the corresponding time increment, or dq=i dt.
electric charge 电荷
integral ['intiɡrəl] n. 积分 increment n. 增量 armature ['ɑ:mə,tjuə, -tʃə] n. 电枢，衔铁，加固 aforementioned [ə'fɔ:,menʃənd] adj. 上述的,前面提到的 represent v. 代表，表示，阐明
翻译： 有源电气元件涉及将其它能量转换为电能，例如，电池中的电能 来自其储存的化学能，发电机的电能是旋转电枢机械能转换的结果。
Active electrical elements occur形容词短语做 in two basic forms: voltage 后置定语 sources and current sources. In their ideal form, voltage sources generate a constant voltage independent of the current drawn from the source. The aforementioned battery and generator are regarded as voltage sources since their voltage is essentially constant with load. On the other hand, current sources produce a current whose magnitude is independent of the load connected to the source. Although current sources are not as familiar in practice, the concept does find wide use in representing an amplifying device, such as the transistor, by means of an equivalent electrical circuit. Symbolic representations of voltage and current sources are shown in Fig.1-1A.
翻译：有源电气元件存在两种基本形式：电压源和电流源。其理想状态为： 电压源两端的电压恒定，与从电压源中流出的电流无关。因为负载变化时 电压基本恒定，所以上述电池和发电机被认为是电压源。另一方面，电流 源产生电流，电流的大小与电源连接的负载无关。虽然电流源在实际中不 常见，但其概念的确在表示借助于等值电路的放大器件，比如晶体管中具 有广泛应用。电压源和电流源的符号表示如图1-1A-2所示。
P1U1A Electrical Networks
1.课文内容简介：主要介绍专业基础课《电路》中 的无源元件和有源元件，基尔霍夫第一定律，由电 阻、电容、电感和直流电压源串联组成的二阶电路 等。 2. 背景知识：这是一篇介绍电路理论的文献。电路 可以分为有源电路和无源电路两种。构成电路的基 本器件有：电压源、电流源、电阻、电感和电容。 对于电路理论，最基本的问题就是列写和求解电路 中各个语 network n. 网络，电路 resistor [ri'zistə] n. 电阻器
resistance:电阻（值） Inductance:电感（系数） capacitance:电容量
inductor n. 电感器
capacitor [kə'pæsitə] n. 电容器 active network 有源网络
Which 做关系 In the case of a resistor, the voltage-current relationship is given 代词引导非限 by Ohm’s law, which states that 制性定语从句 the resistor is the voltage across equal to the current through the resistor multiplied by the value of the resistance.
amplify ['æmplifai] v. 放大
symbolic[sim'bɔlik] adj. 符号的，记号的
mesh [meʃ] n. 网孔
Kirchhoff’s first law 基尔霍夫第一定律 loop[lu:p] current ['kʌrənt] 回路电流 voltage ['vəultidʒ] drop 电压降
A common method of analyzing an electrical network is mesh or loop analysis. The fundamental law that is applied in this method is Kirchhoff’s first law, which states that the algebraic sum of the voltage around a closed loop is 0, or, in any closed loop, the sum of the voltage rises must equal the sum of the voltage drop. Mesh analysis consists of assuming that currents—termed loop currents— flow in each loop of a network, algebraically summing the voltage drops around each loop, and setting each sum equal to 0.
in series 串联 differential adj. 微分的；n. 微分 variable['vεəriəbl] n. 变量
Proportion Integral Differential
outline ['autlain] n. 轮廓；v. 提出……的要点 eliminate [i'limineit] v. 消除，对消 课文中生词 resultant adj. 作为结果而发生的；n.结果