Modern PhysicsModern Physics1

Programm

Special Relativity Galileo and Lorentz transformation Special Relativity – Galileo and Lorentz transformation. Wave - particle dualism of light Quantum mechanics postulates. Schrodinger equation and its

application (quantum well tunneling effect)application (quantum well, tunneling effect). Quantum effects: lasers, electron and tunneling microscopes. Hydrogen atom. Quantum numbers. Spin. NMR operation.

M l t t M l l b di S lid t t Many – electron atom. Molecular bondings. Solid state bondings.

Crystal structures . Band theory of solids. Metals, insulators, semiconductors superconductors high and low temperaturesemiconductors, superconductors high and low temperature.

Dynamics of electrons in a solid state. Electrons and holes in Semiconducting nanostructures. N l St d k f Nucleus. Strong and weak forces Fusion and fission reactions. Elementy particles. The Universe time line

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TEXT BookTEXT Book

Elementary modern physics. Ri h d T W id R b t L S llRichard T. Weidner, Robert L. SellsQuantum Physics.Quantum Physics.

Robert Martin EisbergElementary Modern Physics.

Atam Parkash AryaAtam Parkash AryaMy Lecture note given in class

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GradingGrading

Homework……………..2 pointsQuizzes 2 pointsQuizzes………………...2 pointsThree Exams……….....9 pointsFinal Exam…………….5 pointsTerm paper 2 points*Term paper…………….2 points*

*- optional: if not will be added to exams

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Understanding the ideas of each lecture requires the knowledge of thelecture requires the knowledge of the

previous lectures.

If you keep upIf you keep up, you won’t end up looking likeup looking like this the night before the quizzes!q

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State of Physics cira 1895State of Physics cira 1895

Conservation Laws• Energy

• Linear & Angular Momentum

Statistical Mechanics• 3 Laws of Thermodynamics

• Kinetic Theory

Electricity & MagnetismMaxwell Equations (c 1880)• Gauss’ Law•Faraday’s Law g• Kinetic Theory Faraday s Law•Ampere’s Law•No magnetic monopoles

Mechanics (Gravity) Newton’s Laws (c 1640)( )1-Law of inertia2-F=ma3-Equal and opposite reactions

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RELATIVISTIC PHYSICSThe study of phenomena

th t t k l ithat takes place in a frame of reference that isframe of reference that is in motion with respect to ot o t espect to

the observer.

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Big Bang Timelineg g

We are here8

Atomic ParticlesAtomic Particles

Atoms are made of protons, neutrons and electrons

99.999999999999% of the atom is empty space Electrons have locations

ldescribed by probability functions

nucleus

mp = 1836 meNuclei have protons and

neutrons

p e

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Atomic sizesAtomic sizes

Atoms are about 10-10 mNuclei are about 10-14 mNuclei are about 10 m Protons are about 10-15 m The size of electrons and The size of electrons and

quarks has not been measured but they are atmeasured, but they are at least 1000 times smaller than a protonthan a proton

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What is Light?What is Light?

Properties of light Reflection Refraction Reflection, Refraction

A property of both particles and wavesInterference and Diffraction Interference and Diffraction Young’s double slits

A P t f W O l A Property of Waves Only Polarisation

A Property of Waves Only

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Classical PhysicsClassical Physics

Light is a waveYoung’s Double Slit Experiment g pFaraday’s experimentsMaxwell’s equationsMaxwell s equations

E0

BE

B 0

JEB

tE

01

t 000

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The Birth of the QuantumThe Birth of the Quantum Max Planck The energy contained in radiation is related

to the frequency of the radiation by the l ti hirelationship

nhnhfE

n is a positive integer called the quantum b

f

number f is the frequency of the oscillation

A di t k t f l t t A discreet packet of energy, later to become known as “a photon”

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Implications of Planck’s Law

The energy levels of the molecules must energy4hf

energy n

be discreetOnly transitions by

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energy4hf3hf2hfOnly transitions by

an amount E=h are allowed

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2hf1hf0allowed

The implication is that light is discreet These quantum levels are now

0

that light is discreet or quantised

These quantum levels are now known as number states

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Photoelectric effect

When light strikes the When light strikes the cathodecathode, electrons , electrons are emittedare emittedare emittedare emittedElectrons moving between the two plates Electrons moving between the two plates constitute a currentconstitute a current 15

Photoelectric EffectPhotoelectric Effect Explanation

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

bby hKmax

Where is known as the “work function”of the materialof the material

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Properties of matterProperties of matter

Consists of discreet particles Atoms Molecules etc Atoms, Molecules etc.

Matter has momentum (mass)A well defined trajectoryDoes not diffract or interfereDoes not diffract or interfere

1 particle + 1 particle = 2 particles

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Louis de Broglie1892 - 1987

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Wave Properties of MatterWave 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, hhE

hc

hcEp

Which says that the wavelength of light is related to itsWhich says that the wavelength of light is related to its Which says that the wavelength of light is related to its Which says that the wavelength of light is related to its momentummomentum

M ki th i f tt fi dM ki th i f tt fi d

hh

Making the same comparison for matter we find…Making the same comparison for matter we find…

mvp

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Quantum TheoryQuantum Theory

Particles act like waves?!The best we can do is predict theThe best we can do is predict the

probability that something will happen.

Heisenberg Dirac Schrodinger 20

Quantum mechanicsQuantum mechanics

Wave-particle duality Waves and particles have interchangeable Waves and particles have interchangeable

properties This is an example of a system with This is an example of a system with

complementary propertiesf The mechanics for dealing with

systems when these properties become y p pimportant is called “Quantum Mechanics”Mechanics

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The Uncertainty Principle

Measurement disturbes the systemMeasurement disturbes the system

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The Uncertainty PrincipleThe Uncertainty PrincipleClassical physics

Measurement uncertainty is due to limitations of Measurement uncertainty is due to limitations of the measurement apparatus

There is no limit in principle to how accurate a 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 t i t i i luncertainty principle

If a measurement of position is made with precision x and a simultaneous measurement ofprecision x and a simultaneous measurement of linear momentum is made with precision p, then the product of the two uncertainties can never be l th h/2less than h/2

xx p 23

The Uncertainty PrincipleThe Uncertainty Principle

Virtual particles: created due to the UP

E t E t

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In Search of the Higgs BosonIn Search of the Higgs Boson

Higgs boson is “cosmic molasses” – the Holy Grail of particle physicsHoly 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=115or disprove initial hints for Higgs at E=115GeV

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ان اشنک’SSتگاخ x،دستگاهبخوانيدSو S’،باشندحرکتدر:

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در اين صورتا

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دستگاهيکبهاينرسیدستگاهيکازکههنگامیپس• یي زیپس ر ي بي و کند نمی تغيير حرکت های معادله رويم می ديگر اينرسی

ناوردانيوتنقوانينگاليلهتبديالتدرديگرعبارتبه ناوردانيوتن قوانينگاليلهتبديالت درديگرعبارتبه.مانند می

ها نهاتگاهتهناظ کختلفا يکمختلف اينرسیهایدستگاه بهپيوستهناظرهای•.کنند می تعبير طور يک را پديده

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ثابت توان نمی مکانيکی آزمايش هيچ ی وسيله به بنابراين•بقيهواستسکونحالدراينرسدستگاهيککهکرد بقيهواست سکونحالدراينرسی دستگاهيککهکرد

.دارند يکنواخت حرکت آن به نسبت

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شنا در طول رودخانهمتحرك محيط در حركت در محيط متحركحركت

u- ساحل به نسبت رودخانه سرعتآ c-ساكنآبدرشناگرسرعت

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شنا در عرض رودخانه

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يگيريمدرسي كه از شناگر مي ر از ي يريمر

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.انيشتين و ديگران عدم وجود اتر را مدعي شدند45

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