9电气工程专业英语

Unit9 Magnetism and ElectromagnetismText A Electromagnetism(1)The discovery of the relationship between magnetism and electricity ,like many other scientific ,was stumbled upon almost by accident.(2) The danish physicist Hans Christian Oersted was lecturing one day in 1820 on the possibility of electricity and magnetism being related to one another ,and in the process demonstrated it conclusively by experiment in front of hie whole class ! (3) By passing an electric current through a metal wire suspended above a magnetic compass , Oersted was able to produce a definite motion of the compass needle in response to the current .⑷What began as conjecture at the start fo the class session was confirmed as a fact at the end.⑸His serendipitous discovery paved the way for a whole new branch of science ; electromagnetics .⑴Detailed experiments showed that the magnetic field produced by an electric current is always oriented perpendicular to the direction of flow . ⑵A simple method of showing this relationship is called the right-hand rule. ⑶Simple stated , the right-hand rule says that the magnetic flux lines produced by a current-carrying wire will be oriented the same direction as the curled fingers of a person’s right hand ,with the thumb pointing in the direction of electron flow ,which is shown in fig 2.1.⑴The magnetic field encircles this straight piece ofcurrent-carrying wire ,the magnetic flux lines having no definite “north”poles.⑴While the magnetic field surrounding a current-carrying wire is indeed insteresting ,it is quite weak for common amounts of current ,able to deflect a compass neddle and not much more . ⑵To create a stronger magnetic field force with the some amount of electric current ,we can warp the wire in to a coil shape ,where thecircling magnetic fields around the wire will jion to create a lager field with a definite magnetic (north an south) polarity . See fig 2.2. Unit9Text A电磁学⑴电学和磁学之间的关系就像科学家说的一样是意外中无意间发现的。

⑵1820年的一天丹麦物理学家奥斯特在讲课中指出电学和磁学之间可能拥有某种关系，并且在讲课的过程中他在全班面前通过做实验结论性的证明了这一点。

⑶奥斯特在悬放于磁罗盘上方金属中通入电流，发现磁罗盘指针明确运动，⑷在课上所做的猜想最后被证明是事实。

⑸他偶然发现的事情为整个新的科学分支--电磁学奠定基础。

⑴详细实验表明电流产生的磁场的方向总是垂直于电流的方向，⑵右手定则是一个可以说明这种关系的简洁方法。

⑶简单的说，右手定位就是当大拇指指向电流的方向时，载流导线所产生礠力线的方向与人的右手四指弯曲方向一致，如图2.1所示。

⑴磁场环境在载流导线的直的部分，礠力线没有明确的南极，北极。

⑴虽然磁场环流导线确实很有趣，但是平时的电流只能让楼盘指针偏转一个很小的角度。

为了使同样大小的角度。

⑵为了使同样大小的电流产生更强的磁场力，我们可以把导线绕城螺旋形，在螺旋线圈中导线周围的圆形磁场可以叠加成一个更强的具有明确极性的磁场,如图2.2所示。

⑴The amount of magnetic field force generated by acoiled wire is proportional to the current through the woremultilied by the number of “turns”or “wraps”of wire in thecoil. ⑵This field force is called magnetomotive force ,and isvery much analogous to electromotive force in an electriccircuit .⑴An electromagnet is a piece of wire intended togenerated a magnetic field with the passage of electric ofelectric current thorugh it . ⑵Though all current carryingconductors produce magnetic field ,an electromagnet isusually constructed in such a way as toimaximize thestrength of the magnetic filed it produce for a specialpurpose . ⑶Electromagnets find frequent application inresearch ,industry ,medical , and consumer products.⑴As an electrically-controllablemagnet ,electromagnets find application in a wide variety of“electromechanical”devices :machines that effectmechanical force or motion through electrical power .⑵Perhaps the most obvious example of such machine is theelectric motor . Another example is the relay, anelectrically-controlled switch .⑶If a switch contactmechanism is built so that it can be actuated by theapplication of a magnetic field ,and an electromagnet coil idplaced in the near vicinity to produce that requisite field ,itwill be possible to open and close the switch by theapplication of a current through the coil . ⑷In effect , thisgives us a fevice that enable electrivity to control electricity .See fig 2.3.⑴导线圈所产生的磁动势的大小与导线中流过的电流和线圈匝数的乘机成正比。

⑵这个场力叫做磁动势它跟电路中的电动势非常相似。

⑴电磁铁是一段通过电流并能产生磁场的导线。

⑵尽管所有的载流导线都能产生磁场，但是为了某种特定的目的，一个电磁铁通常以某种方式被构造，在这种方式下它产生的磁场能达到最大幅值。

⑶电磁体被频繁的应用在研究，工业，医学，和日常民用电中。

⑴最为一个电控磁铁，电磁铁被广泛的应用在各种机械设备中:通过电力影响机械力或机械运动的机械。

⑵也许最常见的例子就是电动机。

另一个就是继电器，一个电控开关。

⑶如果构造一个可以通过应用磁场开通或关断的触头装置并且一个电磁线圈被她放在附近来生所需的磁场。

⑷事实上，这给了我们一个能够使用电控制电成为可能的装置，如图2.3所示。