一、简答题(9x5=45%) 1. What is meant by "Tranverse Doppler Effect" Ans:横向都卜勒效应:一般讨论都卜勒效应,都是针对光源(S)与侦测器(D)在一直线上彼此 接近或远离的情况,然而当S移动的路线不会经过D,当S的速度V垂直於S与D的连线时,也 就是S与D距离最短时,此瞬间S既不是接近亦不是远离D,此时的都卜勒效应称为横向都 卜勒效应(若S发射的是声波则没有都卜勒效应) 2. Explain that how optical fiber transmit signal Ans:光在optical fiber(光纤)内壁进行多次全反射 3. Light travels in vaccum with wavelenth λ and velocity c. What are the corresponding wavelength and velocity of the light when it is traveling in a medium with refractive index n? Ans:λ'=λ/n , v=c/n 4.The important four electromagnetic laws are gererally known as the Maxwell equations. Yet, curiously enough, Maxwell completely did not have a hand in three of the four equations, with exceptions called the Ampere-Maxwell law. Explain why shoulld these equations called the "Maxwell equations"? Ans:因为马克斯威尔最早提出这些公式的原形 (onepiece584更正:Maxwell提出重要的一条，让电学和磁学建立关系， 四条式子并非全Maxwell提出) 5.Why an incident light changes its phase by π when it is reflected from an interface with higher refraction index? 不会=ˇ= 6.Give a sample explanation of what is meant by Scanning Tunneling Microscope or simply STM? Ans:是一种利用量子理论中的隧道效应探测物质表面结构的仪器。它主要是利用一根非常 细的金属探针，针尖的电子会跳到待测物体表面上形成穿隧电流，同时，物体表面的高低 会影响穿隧电流的大小，针尖随着物体表面的高低上下移动以维持稳定的电流，依此来观 测物体表面的形貌。 7.Why Einstein;s theory of "photoelectric effect" is so important? Ans:说明了光有粒子性,使光量子理论被接受 8.In 1923, Authur Compton successfully demonstrated his well known "Compton scattering" experiment. What has he proved? What is the Compton wavelength. Ans:证明光不仅仅具有波动性，光在某种情况下也能表现出粒子性。 当X射线或伽玛射线的光子跟物质交互作用时，会失去能量而导致波长变长。 △λ=h/mc(1-cosφ) 9.An electron is trapped in an 1-dimemsional infinite potential well of width b.WRITE down the normalized wave function and the quantized energy levels En Ans: +∞ ∫-∞ ψn^2 (x)dx=1 , ψn^2 (x) =A^2(sin(nπx/b)^2 , A =(2/b)^(1/2) En=(nh)^2/(8m(b^2)),n=1,2,3… (这题不是很确定,麻烦认真的小孩检查一下罗!多谢!) 我不会第五题,然後简答有可能有错=口=,如果有看到麻烦说一声阿!! 95下期末的第三题 3. Explain the followings. (a) What is the photoelectric effect? Give a least one example of application by this effect. ANS: (a) 如果一束光的波长够短,将它照在一个乾净的金属表面上,则光可将电子击出金 属表面 /数位相机、数位摄影机 (b) What is Lorentz transformation?(劳伦兹转换) ANS: 是观测者在不同惯性座标之间对物理量进行测量时所进行的转换关系 (c) What is time dilation? ANS: 当两事件在惯性座标的相同位置发生,则在此座标所测的时间间隔称为原时距,从任 何其他惯性座标所测得的时间间隔必大於原时距,此时距相对於原时距,增加的部分称为 time dilation(时间膨胀) 5. Write down the Maxwell equations and explain the meaning of each equation in detail. (12%) 详见课本内容 --

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