专业英语重点语句译文

第一章1

①Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs (C).

电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。

②We also know that the charge e on an electron is negative and equal in magnitude to 1.60210×10 19C, while a proton carries a positive charge of the same magnitude as the electron.

我们还知道电子的电量是负的并且在数值上等于1.602100×10-12C，而质子所带的正电量在数值上与电子相等。

③A unique feature of electric charge or electricity is the fact that it is mobile; that is, it can be transferred from one place to another, where it can be converted to another form of energy.

电荷或电的特性是其运动的特性，也就是，它可以从一个地方被移送到另一个地方，在此它可以被转换成另外一种形式的能量。

④Although we now know that current in metallic conductors is due to negatively charged electrons, we will follow the universally accepted convention that current is the net flow of positive charges.

虽然我们现在知道金属导体中的电流是由负电荷引起的，但我们将遵循通用的惯例，即把电流看作是正电荷的单纯的流动。

⑤The way we define current as i in Eq. (1-l) suggests that current need not be a constant-valued function, charge can vary with time in several ways that may be represented by different kinds of mathematical functions.

我们通过方程（1－1）定义电流的方式表明电流不必是一个恒值函数，电荷可以不同的方式随时间而变化，这些不同的方式可用各种数学函数表达出来。

⑥The voltage u ab between two points a and b in an electric circuit is the energy (or work) needed to move a unit charge from a to b;

电路中a、b两点间的电压等于从a到b移动单位电荷所需的能量（或所需做的功）。

⑦The power absorbed or supplied by an element is the product of the voltage across the element and the current through it.

某一元件吸收或提供的功率等于元件两端电压和通过它的电流的乘积。

第一章2

①An ideal independent source is an active element that provides a specified voltage or current that is completely independent of other circuit variables

一个理想的独立源是产生完全独立于其它电路变量的特定电压或电流的有源元件。

②The symbol for a voltage source having u volts across its terminals is shown in Fig.1-4(a).

该电压完全独立于流过元件的电流，在其端部具有u伏电压的电压源的符号如图1－4（a）所示

③Another symbol that is often used for a constant voltage source, such as a battery with U volts across its terminals, is shown in Fig.1-4(b).

对于恒定电压源我们通常使用另一种符号，例如在两端只有U伏电压的电池组，如图1－4（b）所示。

④We might observe at this point that the polarity marks on Fig.1-4(b) are redundant since the polarity could be defined by the positions of the longer and shorter lines.

我们可能已经注意到这一点，即图1－4（b）中的极性标号，是多余的因为我们可以根据长天线的位置符，确定电池极性。

⑤Thus if u is the voltage across the source and its current i is directed out of the positive terminal, then the source is delivering power, given by p = ui, to the external circuit.

因此如果u是电源两端的电压而电流i直接从其正端流出，那么该电源正在向对电路释放功率，由式p＝ui 算出。

⑥Since the control of the dependent source is achieved by a voltage or current of some other element in the circuit, and the source can be voltage or current, it follows that there are four possible types of dependent sources,