Elementary modern physics. Elementary Modern Physics.

Transcription

1 Modern Physics 1

2 Programm Special Relativity Galileo and Lorentz transformation. Wave - particle dualism of light Quantum mechanics postulates. Schrodinger equation and its application (quantum well, tunneling effect). Quantum effects: lasers, electron and tunneling microscopes. Hydrogen atom. Quantum numbers. Spin. NMR operation. Many electron atom. Molecular l bondings. Solid state t bondings. Crystal structures. Band theory of solids. Metals, insulators, semiconductors, superconductors high and low temperature. Dynamics of electrons in a solid state. Electrons and holes in Semiconducting nanostructures. Nucleus. Strong and weak forces Fusion and fission reactions. Elementy particles. The Universe time line 2

3 TEXT Book Elementary modern physics. Richard T. Weidner, Robert L. Sells Quantum Physics. Robert Martin Eisberg Elementary Modern Physics. Atam Parkash Arya My Lecture note given in class 3

4 Grading Homework..2 points Quizzes...22 points Three Exams...9 points Final Exam.5 points Term paper.2 points* *- optional: if not will be added to exams 4

5 Understanding the ideas of each lecture requires the knowledge of the previous lectures. If you keep up, you won t end up looking like this the night before the quizzes! 5

6 State of Physics cira 1895 Statistical Mechanics 3 Laws of Thermodynamics Kinetic Theory Electricity & Magnetism Maxwell Equations (c 1880) Gauss Law Faraday s s Law Ampere s Law No magnetic monopoles Conservation Laws Energy Linear & Angular Momentum Mechanics (Gravity) Newton s Laws (c 1640) 1-Law of inertia 2-F=ma 3-Equal and opposite reactions 6

7 RELATIVISTIC PHYSICS The study of phenomena that t takes place in a frame of reference that is in motion o with respect to the observer. 7

8 Big Bang Timeline We are here 8

9 Atomic Particles Atoms are made of protons, neutrons and electrons % of the atom is empty space Electrons have locations described by probability functions Nuclei have protons and neutrons nucleus m p = 1836 m e 9

10 Atomic sizes Atoms are about m Nuclei are about m Protons are about m Thesizeofelectronsand electrons quarks has not been measured, but they are at least 1000 times smaller thanaproton a 10

11 What is Light? Properties of light Reflection, Refraction A property of both particles and waves Interference and Diffraction Young s double slits AP Property of fwaves Only Polarisation A Property of Waves Only 11

12 Classical Physics Light is a wave Young s Double Slit Experiment Faraday s experiments Maxwell s equations E 0 B 0 B E t 1 B 0 0 E t J 12 0

13 The Birth of the Quantum Max Planck The energy contained in radiation is related to the frequency of the radiation by the relationship E nhf nh n is a positive integer called the quantum number f is the frequency of the oscillation A discreet packet of energy, later to become known as a photon 13

14 Implications of Planck s Law The energy levels of the molecules must be discreet Only transitions by an amount E=h are allowed The implication is that light is discreet or quantised energy energy 4hf 3hf 2hf 1hf 0 n These quantum levels are now known as number states 14

15 Photoelectric effect When light strikes the cathode, electrons are emitted Electrons moving between the two plates constitute a current 15

16 Explanation Photoelectric Effect Einstein: the quanta of energy are in fact localised particle like energy packets Each having an energy given by hf Emitted electrons will have an energy given by K max h Where is known as the work function of the material 16

17 Properties of matter Consists of discreet particles Atoms, Molecules etc. Matter has momentum (mass) A well defined trajectory Does not diffract or interfere 1 particle + 1 particle = 2 particles 17

18 Louis de Broglie

19 Wave Properties of Matter In 1923 Louis de Broglie postulated that perhaps matter exhibits the same duality that light exhibits Perhaps all matter has both characteristics as well For photons, p E c h h c Which says that the wavelength of light is related to its momentum Mki Making the same comparison for matter we find fid h p h mv 19

20 Quantum Theory Particles act like waves?! The best we can do is predict the probability that something will happen. Heisenberg Dirac Schrodinger 20

21 Quantum mechanics Wave-particle duality Waves and particles have interchangeable properties This is an example of a system with complementary properties The mechanics for dealing with systems when these properties p become important is called Quantum Mechanics 21

22 The Uncertainty Principle Measurement disturbes the system 22

23 The Uncertainty Principle Classical physics Measurement uncertainty is due to limitations of the measurement apparatus There is no limit in principle to how accurate a measurement can be made Quantum Mechanics There is a fundamental limit to the accuracy of a measurement determined by the Heisenberg uncertainty t principle i If a measurement of position is made with precision x and a simultaneous measurement of linear momentum is made with precision p, then the product of the two uncertainties can never be less than h/2 x p x 23

24 The Uncertainty Principle Virtual particles: created due to the UP E t 24

25 In Search of the Higgs Boson Higgs boson is cosmic molasses the Holy Grail of particle physics Interactions with the Higgs Field are theorized to give all the particles their masses LHC detectors should be able to confirm or disprove initial hints for Higgs at E=115 GeV 25

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27 relativevelocity.html (Command Line) 27

28 دستگاههای مختصات اينرسی - نسبيت اين اينرسیاتا استوار ااست. دستگاه های براساس نيوتن قا قوانين مطلب در قانون اول نيوتن کد شده است. اگر در يک دستگاه مختصات به يک جسم نيرويی وارد نشود را ادامه دهد خود يکنواخت حرکت به يا ساکن و جسم ا ن و ا ن دستگاه مختصات را اينرسی گويند. دارند. يکنواخت حرکت هم به اينرسی نسبت دستگاههای اگر دو دستگاه اينرسی که نسبت به هم با سرعت V در جهت باشند: حرکت S در و دستگاه S بخوانيد x 28

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34 و همين طور و اين صورت در 34

35 سپ یماگنه هک زا کي هاگتسد یسرنيا هب کي هاگتسد سپ ی ز ي ی ر ي ب ي یسرنيا رگيد ميوریم هلداعم یاه تکرح رييغت دنکیمن و هب ترابع رگيد رد تلايدبت هليلاگ نيناوق نتوين ادروان هب ترابع رگيد رد تلايدبت هليلاگ نيناوق نتوين ادروان.دننامیم اه ظان هت ه اگت اه نا فلتخ ک یاهرظان هتسويپ هب یاههاگتسد یسرنيا فلتخم کي هديدپ ار کي روط ريبعت.دننکیم چيه یهديدپ یکيناکم دناوتیمن نيب یاهمتسيس یسرنيا توافت دراذگب. و ر ب. نياربانب هب یهليسو چيه شيامزا یکيناکم ناوتیمن تباث درک هک کي هاگتسد سرنيا رد لاح نوکس تسا و هيقب درک هک کي هاگتسد یسرنيا رد لاح نوکس تسا و هيقب تبسن هب نا تکرح تخاونکي.دنراد 35

36 شکل تغيير تبديلات اين تحت ماکسول معادلات اما میدهند. پس میتوان با استفاده از پديدههای الکترومغناطيسی بين دستگاههای اينرسی مختلف تمايز قاي ل شد. 36

37 شنا در طول رودخانه حركت در محيط متحرك u- سرعت رودخانه نسبت به ساحل آب ساكن c- سرعت شناگر در 37

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39 39 شنا در عرض رودخانه

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41 41 يگيريم درسي كه از شناگر مي

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45 45 انيشتين و ديگران عدم وجود اتر را مدعي شدند.

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