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Giáo trình Tiếng Anh nâng cao chuyên ngành Vật lý: Phần 1

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Giáo trình tập trung vào 4 môn học cơ bản của chuyên ngành Vật lý mà người học cũng được học bằng tiếng Việt nên thuận lợi trong việc tiếp thu và rất hữu ích vì các kiến thức này không những cần cho sinh viên, học viên cao học mà cho bất kỳ một người nào làm việc về Vật lý. Nội dung giáo trình được biên soạn thành 5 chương, trong đó 4 chương đầu bao gồm các nội dung về cơ học lý thuyết, điện động lực học, cơ học lượng tử, vật lý thống kê. Chương cuối cùng là phần hướng dẫn tài liệu tự học. Giáo trình được chia thành 2 phần, mời các bạn cùng tham khảo phần 1 sau đây.

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Nội dung Text: Giáo trình Tiếng Anh nâng cao chuyên ngành Vật lý: Phần 1

  1. Tron Bo SGK: https://bookgiaokhoa.com NGUYỄN VĂN HÙNG TIẾNG ANH NÂNG CAO CHUYÊN NGÀNH VẬT LÝ ADVANCED ENGLISH FOR PHYSICISTS NHÀ XUẤT BẢN ĐẠI HỌC QUỐC GIA HÀ NỘI Download Ebook Tai: https://downloadsachmienphi.com
  2. Tron Bo SGK: https://bookgiaokhoa.com content 3 CONTENT Page P reface.......................................... ................................................................................5 Giới thiệu giáo trình Tiếng A nh tĩảngcao chuyên ngành Vật l ý ...................................7 Chapter I : T h e o re tic a l M echanics.........................................................................9 Part 1.1: Reading, English-Vietnamese translation................................................... 9 Part 1.2: Vietnamese-English translation.................................................................40 Part 1.3: Answer the below questions in English.....................................................45 ■Part 1 .4: Topics for report and discussions in English........................................... 49 Part 1 .5 : Supplementary materials for reading and translation............................50 C h apter!: E le c tro d y n a m ic s ................................................................................. 51 Part 2.1: Reading, English-Vietnamese translation................................................ 51 Part 2.2: Vietnamese-English translation................................................................ 94 Part 2.3: Answer the below questions in English...................................................100 Part 2.4: Topics for report and discussions in English......................................... 103 Part 2.5: Supplementary materials for reading and translation......................... 104 Chapter 3: Q u a n tu m m echanics........................................................................107 Part 3.1: Reading, English-Vietnamese translation...............................................107 Part 3.2: Vietnamese-English translation...............................................................156 Download Ebook Tai: https://downloadsachmienphi.com
  3. Tron Bo SGK: https://bookgiaokhoa.com 4 ADVANCED ENGLISH FOR PHYSICISTS Part 3.3: Answer the below questions in English................................................... 161 Part 3.4: Topics for report and discussions in English.........................................1 64 Part 3.5: Supplementary materials for reading and translation..........................166 Chapter 4: Statistical Physics............................................................................167 Part 4.1 : Reading, English-Vietnamese translation............................................... 1 67 Part 4.2: Vietnamese-English translation.............................................................. 205 Part 4.3: Answer the below questions in English...................................................2 1 1 Part 4.4: Topics for report and discussions in E nglish....................................... 214 Part 4.5: Supplementary materials for reading and translation......................... 2 15 Chapter 5: Practice o f writing scientific report or p ap er.......................... 217 Part 5.1 : Plan of writing a scientific report or paper............................................. 217 Part 5.2: An example o f a published paper........................................................... 219 Appendix: New W ords........................................................................................ 231 R eferences.................................................................................. ............................. 251 Download Ebook Tai: https://downloadsachmienphi.com
  4. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISI I FOR PHYSICISTS 5 PREFEACE This teaching material “Advanced English for Physicists” has been written based on teaching materials of the author (Prof. Dr. sc. Nguyen Van Hung) for undergraduate (H onors Program, 3rd year) and Master’s students of the faculty of Physics, Hanoi University of Science in the recent years. A. Purposes: This teaching material has purposes to train the following skills of students on: 1. Reading, translating and writing English physics materials; 2 . Speaking and discussion in English on fundamental subjects of physics. B. Subjects for teaching and training: Main subjects o f Physics have been chosen: Theoretical Mechanics, Electrodynamics, Q uantum Mechanics and Statistical Physics. T he knowledge of these subjects with their new words and use in Physics is important not only for students but also for all physicists. C. Training procedure is realized in each chapter by the following steps: 1. Reading and English-Vietnamese translation. 2. Vietnamese-English translation. 3. Answer questions in English. 4. Presentation and discussions of physics topics in English. 5. Selfstudy of students using supplementary materials. 6. Writing and presenting a scientific report or paper. D. T he new words concerning present teaching material has been provided to help students and teachers in using this material. E. T he author welcomes any comments to improve this teaching material. February 2007. The author Download Ebook Tai: https://downloadsachmienphi.com
  5. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 7 G IỚ I T H IỆ U G IÁ O T R ÌN H TIẾNG ANH n a n g CAOCHƯYÊN n g à n h v ậ t lý I. MỤC ĐÍCH CỦA GIÁO TRÌNH • Đưa viộc giảng dạy ticng Anh chuyên ngành Vật lý ón định có chương trình và giáo trình cụ thc. • Giúp các giáo vièn tham gia giảng dậy có giáo trình đế việc giảng dậy và học tập dược thuận lợi hơn. • Cung cãp cho sinh vicn, học viên cao học và nghiên cứu sinh chuyên ngành Vật lý một tài liệu học tập, trong đó đói với học viên cao học giáo viên sẽ láy một sổ phán chính, rút gọn cho thích hợp với thời lượng cũng như mục đích của việc học. • Thông qua việc học có thé nâng cao nhận thức của người học vé những ván dé cơ bàn của chuyên ngành Vật lý. • Đói với toàn bộ giáo trình có thé đạt mục đích ròn luyện cho người học các kỹ năng quan trọng như: đọc, dịch xuôi, ngược, nói, viét các ván đé Vật lý bằng tiéng Anh. II. NỘI DUNG CỬA GIÁO TRÌNH • Giáo trình góm 5 chương với phán Phụ lục dành cho các từ mới chuyên mòn Vật lý liên quan đén các tài liệu được dạy và cuói cùng là Tài liệu tham khảo. Download Ebook Tai: https://downloadsachmienphi.com
  6. Tron Bo SGK: https://bookgiaokhoa.com 8 PREFRACE • Việc ròn luyện các kỹ năng của người học được thế hiện trong việc giàng dạy của từng chương, bao góm: - Tập dọc và dịch các tài liệu Vật lý từ Anh sang Việt. - Tập dịch các tài liệu Vật lý từ Việt sang Anh. - T ập đặt cầu và trả lời các vấn đé Vật lý bâng tiếng Anh. - Tập trình bày và thảo luận các nội dung Vật lý bằng tiếng Anil. - Chương 5 dành cho việc rèn luyện người học viét và trình bày một bản báo cáo hay một bài báo vé Vật lý bảng tiéng Anh. - Lưu ý là với cao học vì thời lượng hạn chế trong 30 tiết học (45phút/tiét) thì giáo viên chi có the ròn luyện hai kỷ năng thứ nhát và thứ hai với nội dung cũng rút gọn. • Chương trình tập trung vào 4 mòn học cơ bản của chuycn ngành Vật lý mà người học cũng được học bâng tiếng Việt nên thuận lợi trong việc tiép thu và rát hữu ích vì các kicn thức này không những cẩn cho sinh viên, học viên cao học mà cho bát kỳ một người nào làm việc vé Vật lý. Nó được thế hiện trong 4 chương đáu của giáo trình: - Chương I: Cơ học lý thuyét (Theoretical Mechanics). - Chương II: Điộn dộng lực học (Electrodynamics). - Chương III: Cơ học lượng tử (Q uantum Mechanics). - Chương IV: Vật lý thống kê (Statistical Physics). - Trong cuối mỗi chương đéu có hướng dẫn các tài liệu tự học hay dược dùng khi chương trình có thèm thời lượng. Giáo trình được viét dựa trên các tài liệu của tác giả đã giảng dạy cho các sinh viên H ệ dào tạo Cử nhân khoa học tài năng, học viên cao học thuộc chuyên ngành Vật lý trong những năm gán đây ncn đã rút được m ột só kinh nghiệm thực tế. Tuy nhiên, đế dậy theo giáo trình này người dạy cấn có một sỗ kién thức Vật lý nhát định. Download Ebook Tai: https://downloadsachmienphi.com
  7. Tron Bo SGK: https://bookgiaokhoa.com CHAPTER 1 THEORETICAL MECHANICS PA RT 1.1: Reading, English- Vietnamese translation Sec 1. Generalized coordinates Frame o f reference: In order to describe the motion of mechanical system, it is necessary to specify its position in space as a function of time. Obviously, it is meaningful to speak of the relative position of any point. For instance, the position of a flying aircraft is given relative to some coordinate system fixed with respect to the earth; the motion o f a charged particle in an accelerator is given relative to the accelerator, etc. T he system, relative to which the motion is described, is called a frame o f reference. Download Ebook Tai: https://downloadsachmienphi.com
  8. Tron Bo SGK: https://bookgiaokhoa.com 10 CHAPTER 1. THEORETICAL MECHANICS Specification o f time As will be shown later, specification of time in general case is also connected with definding the frame of reference in which it is given. T he intuitive conception of universal, unique time, to which we are accustomed in every day life, is, to a cetain extent, an approximation that is only true when the relative speeds of all material particle are small in comparison with the velocity of light. The mechanics of such slow movements is termed Newtonian, since Isaac Newton was the first to formulate its laws. N ew ton’s laws permit a determitation of the position of a mechanical system at an arbitrary instant of time, if the positions and velocities of all points of the system are known at some initial instant, and also if the forces acting in the system are known. Degrees o f freedom o f a mechanical system The number of independent parameters defining the position of a mechanical system in space is termed the number of its degrees o f freedom. The position of particle in space relative to other bodies is difined with the aid o f three independent parameters, for example, its Cartesian coordinates. The position of a system consisting o f N particles is determined, in general, by 3N independent parameters. However, if the distribution of points is fixded in any way, then the number of degrees o f freedom may be less than 3N. For example, if two point are Download Ebook Tai: https://downloadsachmienphi.com
  9. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 11 constrained by some form o f rigid nondeformable coupling, then, upon the six Cartesian coordinates o f these points, Xi.yi, Z1.x2.y2, Z2, is imposed condition (x 2- x i ) 2+(y 2- y i ) 2+(z 2- z , ) 2= R?2, (l.l) where R 12 is the given distance between the points. It follows that the Cartesian coordinates are no longer in d ep en d en t parameters: a relationship exists between them. Only five o f the six values X j,...,z 2 are now independent. In other words, a system o f two particles, separared by fixed distance, has five degrees of freedom. If we consider three particles which are rigidly fixed in a triangle, then the coordinates o f the third particle must satify the two equations: (x3-xi)2 +(y 3-yi) 2+(z3-zi)2= R 2,, (1.2) (x 3-x2) 2 +(y 3-y2) 2+(z 3-z2) 2= R 32 . (1.3) Thus the nine coordinates of the vertices of the rigid triangle are defined by the three equations ( l . l ) , ( 1 .2 ) and ( 1 .3 ), and hence only six of the nine quantities are independent. T h e triangle has six degrees of freedom. Download Ebook Tai: https://downloadsachmienphi.com
  10. Tron Bo SGK: https://bookgiaokhoa.com 12 CHAPTER 1. THEORETICAL MECHANICS T h e position of a rigid body in space is defined by three points which do not lie on the same straight line. These three points, as we have just seen, have six degrees of freedom. It follows that any rigid body has six degrees of freedom. It should be noted that only such motions o f the rigid body are considered as, for example, the rotation of a top, where no noticeable deformation occurs that can affect its motion. Generalized coordinates It is not always convenient to describe the position of a system in Cartesian coordinates. As we have already seen, when rigid constraints exist, Cartesian coordinates must satisfy supplementary equations. In addition, the choice of coordinate system is arbitrary and should be determined primarily on the basis of expediency. For instance, if the forces depend only on the distances between particles, it is reasonable to introduce these distances into dynamical equations explicitly and not by means of Cartesian coordinates. Download Ebook Tai: https://downloadsachmienphi.com
  11. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 13 In other words, a mechanical system can be described by coordinates whose number is equal to the num ber o f degrees o f freedom o f the system. These coordinates may sometimes coincide with the Cartesian coordinates of some of the particles. For example, in a system o f two rigidly connected points, these coordinates can be chosen in the following way: the position o f one o f the points is given in Cartesian coordinates, after which the other point will always be situated on a sphere whose centre is the first point. T he position o f the second point on the sphere may be given by its longitude and latitude. Together with the three Cartesian coordinates o f the first point, the latitude and longitude of the second point completely define the position o f such a system in space. Download Ebook Tai: https://downloadsachmienphi.com
  12. Tron Bo SGK: https://bookgiaokhoa.com 14 CHAPTER 1. THEORETICAL MECHANICS For three rigidly bound points, it is necessary, in accordance with the method just described, to specify the position of one side of the triangle and the angle of rotation o f the third vertex about that side. T he independent parameters which define the position o f a mechanical system in space are called its generalized coordinates. We will represent them by the symbol qa, where the subscript a signifies the num ber o f the degree of freedom. As in the case of Cartesian coordinates, the choice o f generalized coordinates is to a considerable extent arbitrary. It must be chosen so that the dynamical laws of motion of the system can be formulated as conveniently as possible. Sec 2. Lagrange's Equation In this section, equations o f motion will be obtained in terms of arbitrary generalized coordinates. In such form they are especially convenient in theoretical physics. Newton’s second law Motion in mechanics consists in changes in mutual configuration of bodies in time. In other words, it is described in terms of the mutual distances, or Download Ebook Tai: https://downloadsachmienphi.com
  13. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 15 lengths, and intervals of time. As was shown in the preceding section, all motion is relative; it can be specified only in relation to some definite frame of reference. In accordance with the level of knowledge of his time, Newton regarded the concept of length and time interval as absolute, which is to say that these quantities are the same in all frames of reference. As will be shown later, N ew ton’s assumption was an approximation. It holds w?hen the relative speeds of all the particles are small compared with the velocity of light; here Newtonian mechanics is based on a vast quantity of experimental facts. Download Ebook Tai: https://downloadsachmienphi.com
  14. Tron Bo SGK: https://bookgiaokhoa.com 16 CHAPTER 1. THEORETICAL MECHANICS In formulating the laws o f motion a very convenient concept is th e material particle, that is, a body w'hose position is completely defined by three: Cartesian coordinates. Strictly speaking, this idealization is not applicable to a n y body. Nevertheless, it is in every way reasonable when the m otion ot a body is sufficiently well defined by the displacement in space of any of its particles (for example, the centre of gravity o f the body) and is independent of rotations o r deformations the body. If we start with the concept of a particle as the fundamental entity of mechanics, then the law of motion (Newton’s second law) is formulated thus: m ^ =F . ( 2. 1 ) dr Here, F is the resultant of the forces applied to the particle (the vector sum d2r of the forces) ,—— is the vector acceleration, the Cartesian components of dt2 which are d 2x d 2y d2z Download Ebook Tai: https://downloadsachmienphi.com
  15. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 17 The quantity m involved in equation ( 2 . 1 ) characterizes the particle and is called its mass. Force and mass Equality (2.1) is the definition of force. However, it should not to be regarded as a simple identity or designation, because ( 2 . 1 ) establishes the form of the interaction between bodies in mechanics and thereby actually describes a certain law of nature. T he interaction is expressed in the form of a differential equation that includes only the second derivatives of coordinates with respect to the time (and not derivatives, say, of the fourth order). In addition, certain limiting assumptions are usually made in relation to the force. In Newtonian mechanics it is assumed that forces depend only on the mutual arrangement of the bodies at the instant to which the equality refers and do not depend on the configuration of the bodies at the previous times. As we shall see later, this supposition about the character of interaction forces is valid only when the speeds of the bodies are small compared with the velocity of light. Download Ebook Tai: https://downloadsachmienphi.com
  16. Tron Bo SGK: https://bookgiaokhoa.com 18 CHAPTER I. THEORETICAL M ECHA NICS The quantity m in equation (2.1) is a characteristic o f the body, its ma:ss. Mass may be determined by comparing the accelerations which the force imparts to different bodies; the greater the acceleration, the less the mass. In order to measure mass, some body must be regarded as a standard. The choice of a standard body is completely independent o f the choice o f standards of length and time. This is what makes the dimension (or unit of measurement) of mass a special dimension, not related to the dimensions of length and time. The properties of mass are established experimentally. Firstly, it can be shown that the mass of two equal quantities of the same substance is equal to twice the mass of each quantity. For example, one can take two identical scale weights and note that a stretched spring gives them equal accelerations. If we join two such weights and subject them to the action o f the same spring which has been stretched by the same the amount as for each weight separately,, the acceleration will be found to be one half what it was. It follows that the overall mass of the weights is twice as great, since the force depends only on the tension of the spring and could not have changed. Thus, mass is an additive quantity, that is, one in which the whole is equal to the sum of the quantities o f each part taken separately. Experiment shows that the principle of additivity of mass is also applied to bodies consisting of different substances. Download Ebook Tai: https://downloadsachmienphi.com
  17. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLIS1 I FOR PHYSICISTS 19 In addition, in Newtonian mechanics, the mass o f a body is a constant quantity which does not change with motion. It must not be forgotten that the additivity and constancy of masses are properties that follow only from experimental facts which relate to very specific forms of motion. For example, a very important law, that of the conservation of mass in chemical transformation involving rearrangement o f the molecules and atoms of a body, was established by M. V. Lomonosov experimentally. Download Ebook Tai: https://downloadsachmienphi.com
  18. Tron Bo SGK: https://bookgiaokhoa.com 20 CHAPTER 1. THEORETICAL M EC H A N ICS Like all laws deduced from experiment, the principle of additivity o f nnass has a definite degree of precision. For such strong interactions as take place in the atomic nucleus, the breakdown of the additivity of mass is apparent. We may note that if instead of subjecting a body to the force of a stretched spring it were subjected to the action of gravity, then the acceleration of a b*ody o f double mass would be equal to the acceleration of each body separately. From this we conclude that the force of gravity is itself proportional to the mass of a body. Hence, in a vacuum, in the absence of air resistance, all bodies fall with the same acceleration. Inertial frames o f reference In equation ( 2 . 1 ) we have to do with the acceleration o f a particle. T h ere is no sense in talking about acceleration without stating to which frame }f reference it is referred. For this reason there arises a difficulty in stating the caiu;e of the acceleration. This cause may be either interaction between bodies o r it may be due do some distinctive properties of the reference frame itself. For example, the jolt which a passenger experiences when a carriage suddenly stiops is evidence that the carriage is in nonuniform motion relative to the earth. Download Ebook Tai: https://downloadsachmienphi.com
  19. Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 21 Let us consider a set of bodies not affected by any other bodies, that is, one tha is sufficiently far away from them. W e can suppose that frame of reference exiits such that all accelerations of the set of bodies considered arise only as a result of the interaction between the bodies. This can be verified if the forces satiify N ew ton’s third law, i.e., if they are equal and opposite in sign for any pair of {-articles (it is assumed that the forces occur instantaneously, and this is true onl/ w'hen the speeds of the particles are small compared with the speed of transmission of the interaction). A frame of reference for which the acceleration o f a certain set o f particles defends only on the interaction between these particles is called inertial frame (o' inertial coordinate system). A free particle, not subject to the action o f any otker body, moves, relative to such a reference frame, uniformly in a straight Download Ebook Tai: https://downloadsachmienphi.com
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