052516 week11 quantum3
- 1. Learning ObjectivesLearning Objectives • Who was involved?Who was involved? • Which experiments were used to help usWhich experiments were used to help us understand?understand? • What are atomic line spectra?What are atomic line spectra? • Which models were used to represent theWhich models were used to represent the atom?atom? • Which equations are fundamental?Which equations are fundamental? • Which ones are handy to know?!Which ones are handy to know?! • What have been the successes of quantumWhat have been the successes of quantum theory?theory? • What are the future applications?What are the future applications? Free powerpoints at http://www.worldofteaching.com
- 2. Albert Einstein 1879-1955Albert Einstein 1879-1955 • We believe in theWe believe in the possibility of a theorypossibility of a theory which is able to give awhich is able to give a complete description ofcomplete description of reality, the laws of whichreality, the laws of which establish relationsestablish relations between the thingsbetween the things themselves and notthemselves and not merely between theirmerely between their probabilities ... GODprobabilities ... GOD DOES NOT PLAY DICE.DOES NOT PLAY DICE.
- 3. Niels Bohr 1885-1962Niels Bohr 1885-1962 • Einstein, DON'T TELLEinstein, DON'T TELL GOD WHAT TO DO!GOD WHAT TO DO! • Those who are notThose who are not shocked when they firstshocked when they first come across quantumcome across quantum mechanics cannotmechanics cannot possibly havepossibly have understood it.understood it.
- 4. Werner Heisenberg 1901-1976Werner Heisenberg 1901-1976 • We have to rememberWe have to remember that what we observe isthat what we observe is not nature itself butnot nature itself but nature exposed to ournature exposed to our method of questioning.method of questioning. • I, at any rate, amI, at any rate, am convinced that HE ISconvinced that HE IS NOT PLAYING ATNOT PLAYING AT DICE.DICE.
- 5. Erwin Schroedinger 1887-1961Erwin Schroedinger 1887-1961 • I do not like it, and I amI do not like it, and I am sorry I ever hadsorry I ever had anything to do with it.anything to do with it. • Had I known that weHad I known that we were not going to get ridwere not going to get rid of this damned quantumof this damned quantum jumping, I never wouldjumping, I never would have involved myself inhave involved myself in this business!this business!
- 6. Prince Louis de BrogliePrince Louis de Broglie 1892-19871892-1987 • Electrons should not beElectrons should not be considered simply asconsidered simply as particles, but thatparticles, but that frequency must befrequency must be assigned to them also.assigned to them also. (1929, Nobel Prize Speech)(1929, Nobel Prize Speech)
- 7. Max Planck 1858-1947Max Planck 1858-1947 • Physics is finished, youngPhysics is finished, young man. It's a dead-endman. It's a dead-end streetstreet.. (from an unknown teacher(from an unknown teacher to Planck consideringto Planck considering Physics at the turn of thePhysics at the turn of the 2020thth century!)century!)
- 9. THE ‘ULTRAVIOLET CATASTROPHE’ 1900 - Rayleigh This was a CLASSICAL prediction, first made in the late 19th century, that an IDEAL BLACK BODY at thermal equilibrium will emit radiation with INFINITE POWER. Max Planck resolved this issue by postulating that electromagnetic energy did not follow the classical description, but could only oscillate or be emitted in DISCRETE PACKETS OF ENERGY proportional to the frequency. He called these packets ‘QUANTA’. υhE = Note: sJxh .10626.6 34− =
- 10. THE PHOTOELECTRIC EFFECT 1905 - Einstein The emission of electrons from a surface (usually metallic) upon exposure to, and absorption of, electromagnetic radiation. The photoelectric effect was explained mathematically by Einstein who extended the work on QUANTA as developed by Planck. φυ −= hKE
- 11. MILLIKAN’S OIL DROP EXPERIMENT 1909 - Robert Millikan This experiment determined the magnitude of the electronic charge, and that it was QUANTISED. This value is approximately Cx 19 106.1 − Note: An electron volt (eV) is the amount of energy it takes to accelerate one electron through a potential of one volt. Thus, 1eV Jx 19 106.1 − ≡
- 12. DE BROGLIE WAVELENGTH Prince Louis de Broglie - 1932 De Broglie discovered that all particles with momentum have an associated wavelength. mv h p h ==λ What is the wavelength of a human being, assuming he/she weighs 70 kg, and is running at 25 m/s?
- 13. NUCLEAR ATOM STRUCTURES 1898 - Thomson
- 14. 1911 -Rutherford
- 17. • General expression:General expression: • Lyman:Lyman: n>1n>1 (ultraviolet)(ultraviolet) • Balmer:Balmer: n>2n>2 (visible)(visible) • Paschen:Paschen: n>3n>3 (infrared)(infrared) • Brackett:Brackett: n>4n>4 (infrared)(infrared) • Pfund:Pfund: n>5n>5 (infrared)(infrared) 2 n hcR En −= −= 22 1 1 11 n R λ −= 22 1 2 11 n R λ −= 22 1 3 11 n R λ −= 22 1 4 11 n R λ −= 22 1 5 11 n R λ
- 18. SUMMARY OF IMPORTANT EQUATIONSSUMMARY OF IMPORTANT EQUATIONS • Energy and frequency:Energy and frequency: • The photoelectric effect:The photoelectric effect: • De Broglie wavelength:De Broglie wavelength: • Angular frequency:Angular frequency: λ υ hc hE == φυ −= hKE mv h p h ==λ fπω 2=
- 19. Equations of interestEquations of interest (non-examinable!)(non-examinable!) • Planck’s constant:Planck’s constant: • Wave vector:Wave vector: • Schroedinger:Schroedinger: π2 h = λ π2 =k Ψ+Ψ∇−= ∂ Ψ∂ V mt i 2 2 2
- 20. Richard Feynman 1918-1988Richard Feynman 1918-1988 • Anyone who has notAnyone who has not been shocked bybeen shocked by quantum physics hasquantum physics has not understood it.not understood it. • The word 'quantum'The word 'quantum' refers to this peculiarrefers to this peculiar aspect of nature thataspect of nature that goes against commongoes against common sense.sense.
- 21. Groucho Marx 1890-1977Groucho Marx 1890-1977 • Very interesting theory - itVery interesting theory - it makes no sense at allmakes no sense at all!!
- 22. QUANTUM THEORYQUANTUM THEORY UsesUses • LASERsLASERs • SemiconductorsSemiconductors • TransistorsTransistors • LEDLED • Night Vision GogglesNight Vision Goggles • CCDCCD • MRI / PETMRI / PET ExplainsExplains • TunnellingTunnelling • Radioactive decayRadioactive decay • Periodic tablePeriodic table (Pauli Exclusion(Pauli Exclusion PrinciplePrinciple explanation toexplanation to Mendeleev’s chart)Mendeleev’s chart)
- 23. THE FUTURE OF QUANTUM?THE FUTURE OF QUANTUM? • Dot LASERsDot LASERs • Logic gatesLogic gates • ComputingComputing • Cryptography / EncryptionCryptography / Encryption • CloningCloning • TeleportationTeleportation