Giáo trình Tiếng Anh nâng cao chuyên ngành Vật lý: Phần 2 cung cấp cho người học những kiến thức về vật lý thống kê (Statistical physics). Phần này cũng hướng dẫn các bạn thực hành viết báo cáo khoa học và trình bày trước lớp. Mời các bạn cùng tham khảo.
Tron Bo SGK: https://bookgiaokhoa.com CHAPTER STATISTICAL PHYSICS PART 4.1: Reading, English-Vietnamese translation See 39 The Equilibrium Distribution o f M olecules in an ideal gas The subject o f statistical physics T he methods of quantum mechanics set out in the third chapter make it possible, in principle, to describe any assembly o f electrons, atoms, and molecules comprising a macroscopic body In practice, however, even the problem o f an atom with two electrons presents such great mathematical difficulties that nobody, so far, has solved it completely It is all the more impossible not only to solve but even to write down the wave equation for a macroscopic body consisting, for example, o f 102' atoms with their electrons •k J Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com CHAPTER STATISTICAL PHYSICS 168 Yet in large systems, we encounter certain general laws of motion for which it is not necessary to know the wave function of the system to describe them Let us give one very simple example of such a law W e shall suppose that there is only one molecule contained in a large, completely empty vessel If the motion of this molecule is not defined beforehand, the probability o f finding it in any half of the vessel is equal to 1/2 If there are two molecules in the same vessel, the probability of finding them in the same half of the vessel simultaneously is equal to ( l / ) 2= l/4 The probability o f finding all of a gas, consisting of N particles, in the same half of the vessel (if the vessel is filled with gas) is ( l / ) N, i.e., an unimaginably small number O n the average, there will always be an approximately equal number of molecules in each half of the vessel The greater the number o f molecules forming the gas, the closer to unity will be the ratio of the num ber of molecules in both halves o f the vessel, no matter at what time they are observed This approximate equality for the number of molecules in equal volumes of the same vessel gives an almost obvious example of a statistical law applicable only to a large assembly of objects In addition to a spatial distribution, molecules possess a definite velocity distribution, which, however, can in no way Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 169 be uniform (if only because the probability of an infinitely large velocity is equal to zero) Statistical physics studies the laws governing the motion of large assemblies of electrons, atoms, quanta, molecules, etc T he problem of the velocity distribution of gas molecules is one of the simplest that is solved by the methods of statistical physics Statistical physics introduces a series of new quantities, which cannot be defined in terms o f single body dynamics or the dynamics o f a small number of bodies An example of such a statistical quantity is temperature, which turns out to be closely related to the mean energy of a gas molecule If a gas is confined only to one half o f a vessel, and the barrier dividing the vessel is then removed, the gas will itself uniformly fill both halves Similarly, if the velocity distribution o f the molecules is disturbed in some way, then, as a result o f collisions between the molecules there will be established a very definite statistical distribution, which, for constant external conditions, will be maintained approximately for an indefinitely long time This example involving collisions shows that regularity in statistical arises not only because a large assembly o f objects is taken, but also because they interact Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com 170 CHAPTER STATISTICAL PHYSICS The statistical law in quantum mechanics Quantum mechanics also describes statistical regularities, but relating to a separate object Here, the statistical regularity manifests itself in a very large number of identical experiments with identical objects, and in no way related to the interaction of these objects For example, the electrons in a diffraction experiment may pass through a crystal with arbitrary time intervals and nevertheless give exactly the same statistical picture for the blackening of a photographic plate as if they had passed through the crystal simultaneously Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 171 Regularities in alpha disintegration cannot be accounted for by the fact that there is a very large num ber of nuclei: since there is practically no interaction between nuclei inducing the process, the statistical character predicted by quantum mechanics is only manifested for a large number of identical objects; it is by no means due to their number In this connection, a description of phenomena in quantum mechanics involves the concept of probability phase, similar to the concept of the phase of a light wave In principle, the wave equation can also be applied to systems consisting o f a large num ber o f particles T he solution of an equation represents a detailed quantum mechanical description of the state of the system Let us suppose that as a result of the solution of the wave equation we have obtained a certain spectrum of energy given values of the system $=&0,&\,&2, in states with wave functions Vo»Vi.V2 »-»Vn - Download Ebook Tai: https://downloadsachmienphi.com (39.1) Tron Bo SGK: https://bookgiaokhoa.com 172 CHAPTER STATISTICAL PHYSICS Then the wave function for any state, as was shown in See 30, can be represented in the form of a sum of -functions of states with definite energy values: (39.2) n The square of the modulus — c n| gives the probability (when the energy of a system in the state vj/is measured) that the result will be the nth value The expansion (39.2) makes it possible to determine not only amplitudes, but also relative probability phases corresponding to a detailed quantum mechanical description of the system The methods of statistical physics make it possible straightway to determine approximately the quantities (on = |c n |2 , i.e., the probabilities themselves omitting their phases For this reason, the wave function of the Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 173 system cannot he determined from them, although it is possible to find the practically important mean values of quantities that characterize macroscopic bodies (for example, their mean energy) In this section we shall consider how to calculate the probabilitycon as applied to an ideal gas Ideal gases An ideal gas is a system of particles whose interaction can be neglected The interaction resulting from collisions between molecules is essential only when the statistical distribution is in the process of being established W hen this distribution becomes established the effect of interaction is very slight As regards condensed (i.e., solid and liquid) bodies, the molecules are all the time in vigorous interaction, so that the statistical distribution depends essentially upon the forces acting between the bodies But even in a gas the particles must not be regarded as absolutely independent For example, Pauli's principle imposes essential limitations on the possible quantum states of a gas W e shall take these limitations into account when calculating probabilities Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com 174 CHAPTER STA TISTICAL PHYSICS The states o f separate particles o f a gas In order to distinguish the states of separate particles from the state of the gas as a whole we shall denote their energies by the letter e and the energy of the whole gas by & Thus, for example, if the gas is contained in a rectangular potential well (see Sec 25), then the energy values for each particle are calculated according to equation (25.19) Let e take on the following series ofvalues: e =e0,e1,e2 en, (39.4) where there are no particles in the state with energy e and in general there are nk particles wit energy ek in the gas Then the total energy o f the gas is ® = £ nkek k (39.5) By giving different combinations of numbers m, we will obtain the total energy values forming the series ( 39 ) Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH FOR PHYSICISTS 175 W e have repeatedly seen that the energy value ek does not yet define the particle states For example, the energy of a hydrogen atom depends only upon the principal quantum number n, so that the atom can have tf states for a given energy [see (33.1)] This number, In1, is called the weight of the state with energy cn But it is also possible to place the system under such conditions that the energy' value defines the energy in principle uniquely W e note, first of all, that in all atoms except hydrogen the energy depends not only on n, but on / also, i.e., on the azimuthally quantum number Further, account of the interaction between spin and orbit shows that there is a dependence of the energy upon the total angular m om entum j and, finally, if the atom is placed in an external magnetic field, the energy also depends upon the projection of angular m om entum on the magnetic field Thus, one energy value mutually corresponds uniquely to one state of the atom Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com 176 CHAPTER S TATISTICAL PHYSICS In a magnetic field all the 2tr states with the same principal quantum number are split W e now consider how the states of a gas in a closed vessel are split W e shall suppose that the vessel is of the form of a box with incommensurable squares of the sides a ^ a i a ] Then, in accordance with equation (25.19), the energy o f the particles is proportional to the quantity 2 where n\, m, tij are positive integers Any combination o f these *1 a2 a3 integers gives one and only one number for the incommensurable values a ,a ,a Therefore, specification of the energy defines all three integers Hi, Hz, n If the particles possess an intrinsic angular momentum , we can, so to speak, remove the degeneracy by placing the gas in a magnetic field (an energy eigen value to which there correspond several states of a system is termed degenerate) We shall first consider only completely removed degeneracy i Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH OI PHYSICISTS 241 Incommensurable: Vố ước, không thống ước Induction: Cãm ứng Inertial frame: Hệ qui chiếu quán tính Initial: Ban đáu Interference: Giao thoa Internal: Bên Interchange: Thay cho Intimately: Bộc lộ Intrinsic: Riêng Intuitive conception: Khai niệm trực giác Instantaneous Tức thời Intricate: Phức tạp, rói ren Inversely: Nghịch dảo Irrespective: Khơng ké đến, bất chắp Invariance: Bát biến J Justifiable: Có lý, bào chữa Justify: Chứng minh dúng, bào chữa K Tính chất dộng học Kinematic property: L Label: Phân loại, đánh Lagging: Trẻ Latitude: Vĩ độ Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com APPENDIX: NEW W ORDS 242 Layer: L6p Least action principle: Nguyen ly tac dung toi thieu Liable: Chiu trach nhipm Limit: Gi6i han Load: Tai (O hm ) Longitude: Kinh dp Light: Anh sang, nhp M ¡Magnitude: Gia trj Manifest: Bay to, bieu lp, tuyen ngon Manipulation: Van dung Macroscopic: Vi mo Magnetic-field flux: Tii thong Magnetic line of force: Tii siic Maintain: Duy tri Manner: Cach, kieu Marvelous: Kyla Measure: Do, cach Mean value: Gia trj trungbinh Merely: Chi la Microscopic: Vi mo Molecule: Phan tii Momentum: Xunglupng Move, motion: Chuyen dong Multiplicand: So bi nhan Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLIS11OF PHYSICIS TS 243 N Neglect: Bo qua Nevertheless: Tuy nhién Needle: Câi kim Node: Biém nüt Nonuniform: Khôngdôngnhât Normal: Phâp tuyén Noteworthy: Bàngchüÿ Notwithstanding: Mac dù, bât châp Numerator: T lỵ sơ Nucleus: Hat nhàn o Obey: T uân theo Object: Vât thé, dôi tU0ng Obvious: Rô rang Observation: Quan sât Ohmic load: Tài Ohm Omit: Lâydi, bôdi Operator: Todn tii Oppose: Ngtfỗic Oscillation, vibration: Dao dụng Oscilloscope: Dao dông kÿ Orbit: Qui dao Overwhelming: Quâ manh Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com 244 APPENDIX: NEW W O RD S P Parallelogram: Hình bình hành Parameter: Tham số Parentheses ( ): Ngoặc don Partial derivative: Đạo hàm riêng; Pattern: Hình, ảnh, tranh Pendulum: Con lác Perceived: Được hiếu Persist: Tốn tại, có chấp Perihelion: Cận nhật Percular: Kỳ dị Permeating: Trải ra, tràn ngập Perfect: Hồn hào Period: Chu kỳ Permutation: Hốn vị Perpendicular: Vng góc Phenomenon: Sự kiện, tượng Phase: Pha dao dộng Phlogiston: Chất lỏng nhiệt Photoeflect: Hiệu ứng quang điện Photographic plate: Đĩa phim ảnh Pile: Sỗ lượng lớn Pitch: Ném bóng, dựng lếu Polar angle: Góc cực Polarization: Phân cực Ponderable: Có ý nghĩa, có trọng lượng Postulate: Tiên dé Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH OF PHYSICISTS 245 Pose: Đua ra, trình báy Possess: chiém hữu, có Potential: Thỗ (năng) Precision, accuracy: Độ xác Preserve: Giữ, bào vệ Principle: Nguyên lý Prime, apostrophe ('): Plìáy Probability: Xác xuất Projection: Hình chiếu Propagate: Truyén di Protagonist: Nhân vật Prove: Chứng minh Property: Tính chát Pronounce: Phát âm Pronounced: Rõ ràng Perturbation: Nhiẻu loạn Q Question mark (?): Dáu hỏi Quantum: Lượng tử Quantity: Đại luợng R Radical: T dế Radius: Bán kính Random: Hỗn độn, ngău nhiên Rare-earth element: Nguyên tó dãt Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com 246 APPENDIX: NEW WORDS Reasonable: Có lý Rectangular: Vng góc Refer: Liên quan Refine, refinement: Lọc luyện, tinh chỗ Resistance: Kháng, trở Reverse transition: Chuyến dịch ngược Retain: Giữ nguyên Replacing: Thay chỏ, thay thé Readily: Sân sàng Rear: Mặt sau Recede: Lùi lại Reduced mass: Khói lượng rút gọn Regularity: Đếu đặn, cân đói, hợp lộ Repulsion, Repel: Đáy Recoil: Giật lùi Re-inforce: Tăngcường Reject: Loại bỏ Resembles: Gióng Restrict: Hạn ché, giới hạn Revolve: Quay quanh Refinement: Tinh ché, lọc tuyổn Rod: Thanh Rolling: Lăn Rule: Định luật, qui luật s Satisfy: Thỏa mãn Scale: Kích thuớc Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH OF IMỈYSICISTS 247 Scalar: Vị hướng Scattering: Tán xạ Seek: Tìm kiém Seem: Dường Sense: Cảm giác, nghĩa Semicolon (;): Chẫm pháy Separate: Phàn biệt Sequence: Trình tự, chuỗi nỗi tiỏp Set out: Khởi hành, trình báy Sharp: Sác nét Shell: Lớp Short range: Khoảng ngán Shortage: Thiếu Shrapnel particle: Hạt mảnh Shot: Bấn Significant, significance: Có nghĩa, quan trọng Simultaneously: Đóng thời Simple pendulum Con lác đơn Sliding: Trượt Smear out: Làm mát Solely: Duy nhát, Solid state: Trạng thái rán Solution: Nghiệm, giái Space: Không gian Speculative: Suy dốn Spatial: Thuộc khơng gian Speed: Vận tốc Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com APPENDIX: NEW W O R D S 248 Specify, Determine: Xác dịnh Split: T ách Spread: Tràn ngập, bao phủ Spiral: Xốn ốc Spring: Lị so Stationary state: Trạng thái dừng State: Trạng thái Stone Hòn đá Stretched: Bị căng Strictly speaking: Nói cách chặt chẽ Strike: Đập vào Subtract: Trừ Supplementary, complementary: Bó sung Subscript: Chi sỗ Sufficient: Đủ Subject: Đặt vào, chủ đé Suspended weight: Trọnv; luợng treo Surface layer: Lớp mặt Subsequent derivation: Dân giải ké tiốp Superfluous: Thừa Symbol: Ký hiệu, biếu tuợng Take smth into account: Tính dển Tall tower: Tháp cao Tangential: Tiếp tuyén Tangible: Xác thực Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH OF PHYSICISTS 249 Target: Bia bán Tension: Sựcăng Tossed: Đuọc ném, liệng Total derivative: Đạo hàm toàn phấn Trajectory: Quĩ dạo Track: Vét, đường Thrown: Ném xuống Turn out: Giải thích Tracing: Tìm đáu vét, báng chứng T raverse: Cắt nhau, giao Trustworthy: Chác chán, tin cậy to the power of 3: Hai mũ ba 23 u Uncertainty relation: Hộ thức bát định Unlike smth: Khơng giỗng Uniform: Đỏng nhát, đéu Universal: Vũ trụ, phó biến Ultraviolet: Tử ngoại Utterly: Hoàn toàn V Vast quantity: Đại lượng rộng lớn Variable: Bién só Velocity: Tóc dộ Vessel: Bình, chậu Vertex: Đinh, chóp Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com 250 APPENDIX: NEW WORDS Verification, verify: Thám định, xác định Vigorous: Mạnh, chặt chẽ Visible: Có thể tháy w Warn: Cảnh báo Wave: Sóng Wavelength: Buớc sóng Weight: Trọng luợng, trọng sổ Well: Hó (thé) X X-ray: Tia X (Tia Rơngen) XAFS (X-ray Absorption Cáu trúc tinh tố hấp thụ tia X Fine Structure): Y Yield: Sản sinh Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENC'.USI I OF PHYSICISTS 251 REFERENCES Kompaneyets A s 1965 Theoretical Physics Mir Pubblishers, Moscow Basdevant J-L 2002 Quantum Mechanics Springer-Verlag, Berlin Heidenberg Jackson J D 1999 Classical Electrodynamics David Halliday, Robert Resnick, 1986 Fundamentals of PJiysics John Wiley&Sons, Inc Gibson, Carol, WandaRusek and Anne Swan: IELTS Test now: Practice in Listening, Reading, Writing and Speaking for the IELTS Test NXB Tp HÓ Chi Minh, Tp HCM Greenall, Simson and Michael Swan 1988 Effective Reading Cambrige University Press, Cambrige Zukowski/Faust, Jean, Susan s Johston, and Clark s Atkinson 1983 Between the Lines: Reading Shillsfor Intermediate-Advanced Students of English as a Second Language Hold, Rinehart and Winston New York Trán Thị Nga 2005 Tiếng Anh Cơ cho Sinh viên Khoa học Tự nhiên NXB Giáo dục, H Nội Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com NHft XUAT GỎN DỌI • HỌC • ỌC Gin NỘI • 16 Hàng Chuối - Hai Bà Trưng - Hà Nôi Điên thoai: Biẽn tảp-Ché (04) 39714896; Kinh doanh:(04) 39724770 : Tổng Biên táp: (04) 39714897: Fax: (04)39714899 Chiu trách nhiệm xu ấ t bán: Qưôc BAO Giám đốc: PHÙNG Tổng biên tập : PHẠM TH Ị THẢM Chiu trách nhiêm nơi dung: Hội địng nghiệm thu Kiáo trình Trướng Dại học Khoa học Tự nhiôrt DHQC1HN Người nhận xét: PGS.TS NGUYỄN đ ì n h d ũ n g ThS TRẨN THỊ NGA NGUYỄN VẮN HÙNG - NGUYỄN THUỶ Biên tập: Chế bản: THANH NHÀN Trinh bày bìa: NGỌC ANH T IẾ N G A N H N Â N G CAO C H U Y Ê N N G À N H V Ấ T LÝ Mã sò: IK-01 ĐI 12010 In 200 cuốn, khổ 17 X24 cm Nhà in Dí 1QGHN Sơ' xuất bản: 716 - 2009/CXB/12 - 121/ĐHQGHN ngày 6/08/2009 Quyết địnli xuất háu sò: 01 KH-TN/XB In xong nộp lưu chiểu quý I nãm 2010 Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com 250 APPENDIX: NEW W O RD S Verification, verify: Thám dinh, xác định Vigorous: Mạnh, chặt chẽ Visible: Có tháy w Warn: Cành báo Wave: Sóng Wavelength: Buớc sóng Weight: T rọng luợng, trọng só Well: Hó (thố) X X-ray: Tia X (Tia Rơngen) XAFS (X-ray Absorption Fine Structure): Cãu trúc tinh té háp thụ tia X Y Yield: Sàn sinh Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com ADVANCED ENGLISH OF PHYSICISTS 251 REFERENCES II Kompancyets A s 1965 Theoretical Physics Mir Pubblishers, Moscow 21 Basdevant J-L 2002 Quantum Mechanics Springer-Verlag, Berlin Heidenberg 3> Jackson J D 1999 Classical Electrodynamics 4k David Halliday, Robert Resnick, 1986 Fundamentals oj Physics John Wilcy&Sons, Inc 5> Gibson, Carol, WandaRusek and Anne Swan: IELTS Test now: Practice in Listening, Reading, Writingand Speaking for the IELTS Test NXB Tp HỔ Chi M in h T p H C M 6) Greenall, Simson and Michael Swan 1988 Effective Reading Cambrige University Press, Cambrige 7\ Zukowsld/Faust, Jean, Susan s Johston, and Clark s Atkinson 19S3 Between the Lines: Reading Skillsfor Intermediate-Advanced Students oj English as a Second Language Hold, Rinehart and Winston New York s.' Trán Thị Nga 2005 Tiêng Anh Cơ cho Sinh viên Khoa học Tự nhiên NXB Giáo dục, Hà Nội Download Ebook Tai: https://downloadsachmienphi.com Tron Bo SGK: https://bookgiaokhoa.com NHft XÍT ÍĨIÌN DỌI HỌC ỌUỐC G in h A NỘI 16 Hàng Chuối - Hai Bà Trưng - Hà Nội Điẽn thoai: Biẽn tâp-Ché bản: (04) 39714896; Kinh doanh:(04) 39724770 : Tổng Biên táp: (04) 39714897: Fax: (04)39714899 Chiu trách nhiệm xu ấ t bản: Giám đốc: PHỪNG QUỐC BẢO Tổng biên tập PHẠM TH Ị TRÂM Chịu trách nhiêm nơi dung: Hội địng nghiệm thu giáo trinh Trường Dại học Khoa học Tụ nhién • ĐHQCÌHN Người nhận xét: PGS.TS NGUYỂN đ ì n h d ù n g ThS TRẨN THỊ NGA NGUYẺN v ã n h ù n g • NGUYỄN THUỶ Biên tập: Chê bàn: THANH NHÀN Trình bày bia: NGỌC ANH T IẾ N G A N H N Â N G CAO C H U YÊN N G À N H V Ậ T L Ý Mã sô: IK-01ĐH2010 lu 200 cuôn, khổ 17 X 24 cm NhÌ! in Đì IQCỈHN Sơ xuất hàn: 716 - 2009/CXB/12 - 121/ĐHQGHN ngày 6/08/2009 Quyết địnli xuất số: 01 Kil-'1'N/XB In xong nộp lưu chiếu quý nàm 2010 Download Ebook Tai: https://downloadsachmienphi.com ... k = ( l / ) N- k (l /2) k , N! k!(N - k)! The sum of all probabilities is, of course, unity: Z