电磁场与电磁波第1讲绪论及矢量乘法.ppt

1,Field and Wave Electromagnetic电磁场与电磁波,2009.2.23,2,自我介绍 姓 名：郝宏刚 单 位：光电工程学院 实验室：1311 1301 联系方式：QQ:54381964 E_mail:,3,4,History,The ability of a piece of amber to attract small items after it had been rubbed was discovered by the Greeks in 600 B.C.The attractive force between a magnet and iron was noted by the Chinese in 300 B.C.,In 1785,French scientist Charles Augustin de Coulomb(17361806)discovered Coulombs law,and it gives the relationship between the force experienced by two small charged objects and the distance between them.,Early in the first century,the compass was invented and it was among the four great inventions in ancient China.Thereafter,the magnetic field of the earth was discovered.,5,In 1820,Danish scientist Hans Christian Oersted(17771851)discovered the magnetic field produced by an electric current.In the same year,French scientist Andre Marie Ampere(17751836)determined the force between two electric currents.,In 1831,British scientist Michael Faraday(1791-1867)discovered the phenomenon of electromagnetic induction and put forth the law of electromagnetic induction,which states that a time-varying magnetic field must give rise to an electric field.,6,In 1873,British scientist James Clerk Maxwell(18311879)postulated the displacement current,which provided the link between a time-varying electric field and a magnetic field.He put on a firm mathematical foundation the laws governing an electromagnetic field.They are known today as the famous Maxwells equations.,A Great Innovation,Around the end of the 19th century,Popov in Russia and Marconi in Italy invented the technology to transmit information using electro-magnetic waves.,These equations state that a time-varying electric field produces time-varying magnetic field and vice versa.Maxwell further predicted the existence of electromagnetic waves,which was demonstrated in 1887 by the experiment conducted by German physicist Heinrich Rudolph Hertz(18571894).,7,Applications,Modern wireless communications,broadcasting,radar,remote control,microwave sensing,wireless networks and local area networks,satellite positioning,optical communications and other information technologies,all of them use electromagnetic waves to transmit information.,Electrostatic xerography,cleaning,and spraying,are all based on the action of electric forces.,Electromagnets,maglev bearings,and maglev vehicles,all of them being based on the action of magnetic forces.,8,The First HTS Maglev Vehicle,Applied Superconductivity R&D Center,SWJTU,Stable!Stable!,9,A Maglev Vehicle in Shanghai,10,Stealth Bomber-B2,11,Stereoscopic Film,12,Global Positioning System GPS,13,教材介绍,电磁场与电磁波(第二版)/国际知名大学原版教材作者：David/K.Cheng出版社：清华大学出版社出版日期：2007-07市场价：￥65.0,14,1 The Electromagnetic Model 2 Vector Analysis 3 Static Electric Fields 4 Solution of Electrostatic Problems 5 Steady Electric Currents 6 Static Magnetic Fields 7 Time-Varying Fields and Maxwells Equations 8 Plane Electromagnetic Waves 9 Theory and Applications of Transmission Lines 10 Waveguides and Cavity Resonators 11 Antennas and Radiating Systems,Contents,15,参考书目 超星数字图书馆电磁场与电磁波周克定电磁场与波D.郑钧 著 赵姚同 黎滨洪 译电磁场理论基础钟顺时 钮茂德工程电磁场基础(工科类)孙敏 孙亲锡 叶齐政 电磁场与电磁波(英文版)杨儒贵 汤姆斯,16,课程的基本要求1.教材:尽量人手一本2.日常要求:按时上课，不得迟到、早退、无故旷课、说话按时交作业，原则上不接收补交作业，即使收了也只是做登记，而不批改；每次批改作业为1/3以上，1/2以下的作业。*按学校规定作业或到课率少于1/3者，取消考试资格（补考也没有资格含重修）3.考试:英文出题，统一命题，统一判卷，统一划线(包括重修学生)闭卷 2小时 平时成绩30卷面成绩70%4.辅导时间：周三 下午 15：00-17：00 地点：1301，1311,17,教学总结：,初考：178人，25人不及格，其中重修10人，30-20分7人，20-10分4人，10分以下9人。,补考：其中通过3人，20-10分3人，10分以下9人，缺考6人。,只要认真学习，别担心，通过不成问题！满足？,18,学习方法(1)试试英文教材吧！(2)理解、记忆、多做练习！(3)端正态度，知难而进！,Crematorium！,挑战一下自己，努力吧，朋友们！,19,1.Introduction2.Vector Addition and Subtraction3.Products of Vectors4.Orthogonal Coordinate Systems 5.Integrals Containing Vector Functions6.Gradient of a Scalar Field7.Divergence of a Vector Field 8.Divergence Theorem9.Curl of a Vector Field10.Stokess Theorem11.Two Null Identities12.Helmholtzs Theorem,Chapter 2Vector Analysis,20,Main topic,1.Scalar and Vector,2.Vector Addition and Subtraction,3.Products of Vectors,21,1.Scalar and Vector,A scalar is completely specified by its magnitude,such as charge,current and energy.,The specification of a vector requires both a magnitude and a direction,such as electric and magnetic field intensities.,Magnitude,Unity vector,22,2.Vector Addition and Subtraction,1).By the parallelogram rule:The resultant C is the diagonal vector of the parallelogram formed by A and B drawn from the same point.,2).By the head-to-tail rule:The head of A connects to the tail of B.The sum C is the vector drawn from the tail of A to the head of B;A,B,and C form a triangle.,23,Vector subtraction can be defined in terms of vector addition in the following way:,24,The vector addition obeys the commutative and associative laws.,3.Products of Vectors,3.1 scalar multiplication,25,3.2 scalar or dot product,The dot product of two vectors(1)is less than or equal to the product of their magnitudes;(2)can be either a positive or a negative quantity,depending on whether the angle between them is smaller or larger than/2 radians(90);(3)is equal to the product of the magnitude of one vector and the projection of the other vector upon the first one;and(4)is zero when the vectors are perpendicular to each other.,26,Two equal vectors dot product:,The dot product is commutative and distributive laws.,Question:,27,3.3 vector or cross product,The vector of cross product of two vectors A and B is a vector perpendicular to the plane containing A and B;its magnitude is ABsin,where is the smaller angle between A and B,and its direction follows that of the thumb of the right hand when the fingers rotate from A to B through the angle(the right-hand rule).,28,3.4 product of three vectors,Scalar triple product:,Note the cyclic permutation of the order of the three vectors A,B,C.,29,Vector triple product:,The equation is known as the“back-cab”rule.,Division by a vector is not defined,and expressions such as k/A and B/A are meaningless.,30,summary,1.Scalar and Vector,2.Vector Addition and Subtraction,3.Products of Vectors,parallelogram rule and head-to-tail rule,31,homework,Thank you!Bye-bye!,答疑安排时间：周三 下午 15：0017：00地点：1301，1311,0,