电气工程专业英语第2章

• specific gravity 比重
• null [zero] gravity 无重力，失重
–charge
n. 负荷, 电荷, 费用, 充电
负电荷 正电荷
• negative charge • positive charge
• charge density 电荷密度
• like-charged 电性相同的
Electric Basic Concept
–nucleus
n.核子['nju:kli:əs]
–atom
–proton
n. 原子['ætəm]
n.质子['prəu,tɒn] n.电子
–electron
• free electron
自由电子
• electrochemical adj. 电气化学的
–neutral state
的百万分之一)
1.Electric charge 电荷 1.1neutral state of an atom 1.1 中性的原子 Elements are often identified by the number of electrons in orbit around the nucleus of the atoms making up the element and by the number of protons in the atom. 元素是通过组成该原子的核子轨道上的电子数及核子中的质子数来区分 的。 A hydrogen atom, for example, has only one electron and one proton. 例如，一个氢原子只有一个电子和一个质子。 An aluminum atom（illustrated）has 13 electrons and 13 protons. 一个铝原子有13个电子和13个质子（如图）。 An atom with an equal number of electrons and protons is said to be electrically neutral. 一个有相同数目的电子和质子数的原子电性呈中性。
– motor n. 电动机
– voltage sources电压源
– a magnetic induction 电磁感应
–terminal
接头 –kilovolt
n.终端,接源自文库端,电路
n. 千伏特
–millivolt
–microvolt
n. 毫伏(特)(=1/1000
伏(特),略作mV或mv) n. 微伏(等于1伏特
2.1units of measurement for current测量电流的单位 The following chart reflects special prefixes that are used when dealing with very small or large value of current:下面的图表反映了处 理很小和很大的电流时的计量单位的词头： Prefix 词头 symbol 符号 decimal 十进制 1kiloampere1千安 1KA 1000A 1milliampere1毫安 1mA 1/1000A 1microamoere1微安 1μA 1/1000000A 2.2 direction of current flow电流的方向 Some authorities distinguish between electron flow and current flow. 一些权威将电子流和电流区分， Conventional current flow theory ignores the flow of electrons and states that current flows from positive to negative. 传统上电流理论忽略电子流，而认为电流是从正极流向负极。 To avoid confusion ,we will use the electron flow concept which states that electrons flow from negative to positive. 为了避免混淆，我们使用电子流概念是电子从负极流向正极。
电场
–lines of force 力线 电流
–electromotive force=EMF 电动势 –counter- electromotive
force=CEMF 反电动势
–potential adj.势的, 位的 • (electric) potential difference
电位差 • a difference by potential
1.3 attraction and repulsion of electric charge电荷之间的吸引和排斥 The old saying, ”opposites attract” is true when dealing with electric charges. 俗话说，“异性吸引”，处理电荷时是正确的。 Charged bodies have an invisible electric field around them. 每个电荷四周有一个看不见的电场。 When two like-charged bodies are brought together, their electric field will work to repel them.当两个电性相同的电荷靠近时电场将相斥， When two unlike-charged bodies are brought together, their electric field will work to attract them.当两个电性不同的电荷靠近时电场将相吸。 The electric field around a charged body is represented by invisible lines of force. 电荷周围的电场通过不可见的电力线表示， The invisible lines of force represent an invisible electric field that causes the attraction and repulsion. 不可见的电力线表示引起吸引和排斥的不可见的电场。 Lines of force are shown leaving a body with a positive charge and entering a body with a negative charge. 正电荷用离开的电力线表示、负电荷用进入的电力线表示。
中性状态,
[nju:'trælət • electroneutrality n.电中性 i]
• be electrically neutral电性呈中 性
–orbit
n.轨道；轨迹
• orbital electron 轨道电子
–gravity
n. 地心引力, 重力
• acceleration of gravity 重力加速度 • the centre of gravity 重心，重点
1.2positive and negative charges 正负电荷 Electrons in the outer band of an atom are easily displaced by the application of some external force. 原子的外圈的电子很容易由于受到外力的作用而被移走。 Electrons which are forced out of their orbits can result in a lack of electrons where they leave and an excess of electrons where they come to rest. 由于电子从轨道移走而造成该原子缺少电子，而移入电子的原子电子 过剩。 The lack of electrons is called a positive charge because ther are more protons than electrons. 使由于质子数多于电子数，缺少电子的成为正电荷。 The excess of electrons has a negative charge.电子过剩的称为负 电荷。 A positive or negative charge is caused by an absence or excess of electrons. 电子不足或过剩产生正或负电荷。 The number of protons remains constant. 质子数始终是恒定不变的。
2. Current电流 Electricity is the flow of free electrons in a conductor from one atom to the next atom in the same general direction. 电是在导体中的从一个原子以相同方向流向下一个原子的自由电子流。 This flow of electrons is referred to as current and is designated by the symbol ”I”. 这种电子流就是电流，由符号表示为“I”。 Electrons move through a conductor at different rates and electric current has different values. 电子以不同的速度流过导体，电流有不同的值。 Current is determined by the number of electrons that pass through a cross-section of a conductor in one second. 电流的大小由在一秒中内流过导体横截面的电子数量所决定。 We must remember that atoms are very small. 我们必须记住原子是非常小的。 It takes about 1,000,000,000,000,000,000,000,000atoms to full one cubic centimeter of a copper conductor. 在一立方厘米的铜导体中有1,000,000,000,000,000,000,000,000个原子。
This number can be simplified using mathematical exponents. 这个数字可以用数学的指数形式来化简， Instead of writing 24 zeros after the number 1,write1024.用1024来代 替24个零。 Trying to measure even small values of current would result in unimaginably large numbers. 试图测量如此微小的电流将产生难以想象的巨大的数字。 For this reason current is measured in amperes which is abbreviated ”amp”. 所以，电流用安培数来度量，安培可以简写为“amps”。 The symbol for amp is the letter: A”.安培可以用符号“A”来表示。 A current of one amp means that in one second about 6.24×1018electrons move through a cross-section of conductor. 一安培的电流意味着在一秒中之内有6.24×1018个电子流过导体的截面。 These numbers are given for information only and you do not need to be concerned with them. 这些数字只是信息，并不需要去关心。 It is important, that the concept of current flow be understood. 但是重要的是理解电流的概念。
–attract
v.吸引
• attraction
– repel v.排斥
n.吸引, 吸引力,
• opposites attract 异性吸引
• repulsion
n.排斥
–magnetic
有吸引力的
adj. 磁的, 有磁性的,
–magnetic field 磁场
–electric field
–current flow
– ignore
vt.忽略，不理睬, 忽视 n. 交流发电机['):ltə,neitə] adj. 交替的
– alternator • alternate
• alternating current 交流电流 • alternating-current 交流（电）的 – generator n. 发电机