吸收(能量).doc

Ch1 Basic Circuit Concepts and LawsTerms Ampere 安培absorb (energy) 吸收(能量)associative direction 关联方向branch current 支路电流circuit model 电路模型conservation law of energy 能量守恒定律constant voltage source 稳压源dependent source 受控源battery 电池deliver (energy) 传送(能量)electric circuit 电路electron 电子electric potential difference 电位差generator 发电机ideal source 理想电源ideal current source 理想电流源ideal voltage source 理想电压源independent source 独立电源internal resistor 内阻instantaneous Power 瞬时功率 Kirchhoffs current law 基尔霍夫电流定律Kirchhoffs voltage law 基尔霍夫电压定律linear resistor 线性电阻loop 回路loud-speaker 扩音机motor 电动机network 网络node 节点non-associative direction 非关联方向non-ideal source 非理想电源Ohms law 欧姆定律open-circuit 开路positive direction 正向positive electric charge 正电荷real (practical) direction 实际方向reference direction 参考方向resistance (resistor) 电阻(电阻)short-circuit 短路supply (energy) 提供(能量)variable 变量Volt 伏特voltage 电压voltage source 电压源 Essential points1 A Circuit ModelEach element in a real circuit can be described as an ideal one which has same main behaviors with the real one. The circuit containing ideal elements is called a circuit model.实际电路中的每一个元件都可以被描述为具有相同功能的理想元件,由理想元件组成的电路,称为电路模型。2 Reference Directions of Current & VoltageThe real direction is difficult to determine in advance. So we introduced an abstract concept “reference direction”. The reference direction is supposed before analyzing the circuit, so it may be different from the real one. When the reference direction is different from the real one, the current (voltage) is regarded as negative; oppositely, it is regarded as positive.在电路分析伊始，实际方向很难确定的。因此我们引入一个抽象的概念“参考方向”，在电路分析前首先假定参考方向，所以它可能与实际方向不同。当参考方向与实际方向相反时，电流（电压）为负值，反之参考方向与实际方向一致时，电流（电压）为正值。3 Ohms Law Since voltage and current are directly proportional for a linear resistor, there exists a proportionality constant R, called resistance. So we have u= Ri, it is called Ohms Law.对一个线性电阻，它两端的电压和流过它的电流成正比，这个比例常数R被称为电阻，且有u= Ri, 称为欧姆定律。4 Power &Instantaneous PowerBy taking the product of a voltage (energy per unit charge) and the related current (charge per unit time), we get a quantity that measures energy per unit time. Such a term is known as power, expressed as p=ui. The power at any instant of time is called instantaneous power.通过计算电压（单位电荷的能量）和电流（单位时间的电荷）的乘积，我们得到一个度量单位时间能量的量，这个量称为功率，即p=ui。在任一瞬间的功率称为瞬时功率。5 Independent sourceThe source whose value is irrelevant with other variables in the circuit is called the independent source.不受电路中其它量影响或控制的电源称为独立电源。6 A NodeA node, in a given circuit, is a connection of two or more elements.在给定电路中，两个或两个以上元件的联接点被称为节点。7 Kirchhoffs Current Laws (KCL)KCL: At any instant of time, for every node of a circuit, the sum of the currents into the node is equal to the sum of the currents out of the node. In other words, for every node of a circuit, the currents algebraically sum to zero. Kirchhoffs current Law is applied to describe the relationship of branch currents that flow into or out a same node and it reveals the essential law of conservation of electric charges.KCL定律：在任一瞬时，对电路的每一个节点，流入节点的电流之和等于流出节点的电流之和；换句话说，对电路的每一个节点，电流的代数和为零。基尔霍夫电流定律用来描述流入或流出同一个节点支路电流的关系；它揭示了电荷守恒定律的本质。8 Kirchhoffs Voltage Laws (KVL)KVL: In traversing any loop in any circuit, at any instant of time, the sum of the voltages having one polarity equals the sum of the voltages having the opposite polarity. In other words, around any loop in a circuit, the voltages algebraically sum to zero.KVL定律：在任一时刻，穿过电路任一闭合回路的正电压之和与负电压之和相等；换句话说，对任一闭合回路，电压的代数和为零。Kirchhoffs voltage law is applied to describe the relationship of voltages that are included in the loop you concern.基尔霍夫电压定律用来描述你所关心的回路所包含的各电压之间的关系。9 Dependent SourcesAn ideal source, either voltage or current, whose value depends upon a variable (usually a voltage or a current) in the circuit to which the source belongs, is called a dependent source.一个理想的电流源或电压源，如果它的值受到电路其它量（通常是一个电压或一个电流）的控制，称它为受控源。There are four kinds of dependent sources which are named as the voltage controlled voltage sourc