自动化专业英语部分课文与翻译.docVIP

An electrical circuit or network is composed 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 resultant combination is an active network. In studying the 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. 　　　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. In the case of a resistor, the voltage-current relationship is given by Ohms law, which ststes that the voltage across the resistor is equal to the current through the resistor multiplied by the value of the resistance. Mathematically, this is expressed as u=iR where u=voltage , V; i=current, A; R=resistance Ω. 　　　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。在数学上表达为:?u=iR (1-1A-1)式中 u=电压，伏特；i =电流，安培；R = 电阻，欧姆。 The voltage across a pure inductor is defined by Faradays law ,which states that the voltage across the inductor is proportional to the rate of change with time of the current through the inductor. Thus we have u=Ldi/dt where di/dt=rate of change of current ,A/s; L=inductance ,H. 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。因此可得到：U=Ldi/dt 式中 di/dt = 电流变化率， 安培/秒； L = 感应系数， 享利。 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 u=1/c fdq where the capacitance C is the proportionality constant relating voltage and charge. By definition, current equals the rate of chan