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Introduction to the experiments of Physics 407

Introduction to the experiments of Physics 407. Franck-Hertz. Franck-Hertz experiment: confirmation of quantized atomic energy levels. 1 st evidence: Spectrum from a low-pressure mercury lamp. Franck-Hertz. Sketch of Franck-Hertz Apparatus. Collecting plate is slightly

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Introduction to the experiments of Physics 407

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  1. Introduction to the experiments of Physics 407

  2. Franck-Hertz Franck-Hertz experiment: confirmation of quantized atomic energy levels 1st evidence: Spectrum from a low-pressure mercury lamp

  3. Franck-Hertz Sketch of Franck-Hertz Apparatus Collecting plate is slightly negative compared to grid – so only those electrons above an energy threshold will reach it. Positively charged grid accelerates electrons + Heated cathode produces electrons Current from collector measured as a function of accelerating voltage. after Krane accelerating voltage

  4. Franck-Hertz Voltage between peaks corresponds to excitation energy 4.9 V

  5. Hall effect Hall effect with negative charge carriers + Fm = magnetic force on negative charge carriers Fe = electric force from charge buildup Direction of conventional Electric current http://hyperphysics.phy-astr.gsu.edu

  6. Hall effect Hall effect in semiconductors Dominated by positive carriers. Dominated by negative carriers.

  7. Johnson noise Cause: Thermal motion Johnson Noise  0 Vrms?? +

  8. Johnson noise Johnson Noise:way to measure Boltzmann’s constant JB Johnson, Physical Review 32 (1928) 97

  9. Brownian motion Nakroshis et al. AJP71(2003) 568 Brownian motion:more evidence for thermal motion Perrin’s Atoms

  10. Chaos State space of a dynamical system IDEAL FRICTION James P. Crutchfield, J. Doyne Farmer, Norman H. Packard, and Robert S. Shaw SCIENTIFIC AMERICAN DECEMBER, 1986 VOL. 254 NO. 12, 46-57.

  11. Chaos Chaos 10,000 red dots Chaotic behavior is characterized by divergence of nearby trajectories. Lyapunov exponent is a measure of this divergence.

  12. 2 slit interference, one photon Two-slit interference one photon at a time:grappling with wave/particle duality Single photon interference: “a phenomenon which is impossible, absolutely impossible to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery.” - Richard Feynman http://www.blacklightpower.com/theory/DoubleSlit/

  13. 2 slit interference, one photon

  14. Faraday effect The Faraday effect 

  15. Faraday effect Right and left circularly polarized light have different indexes of refractions http://www.ifm.liu.se/~ulfek/viz/

  16. Faraday effect Verde constant depends on wavelength Jain, Am. J. Phys. 67, August 1999, 714

  17. The Zeeman effect Zeeman effect

  18. Zeeman effect The Zeeman effect: Mercury energy levels

  19. Zeeman effect Fabry-Perot distinguishes wavelengths

  20. Optical Pumping

  21. Optical pumping F=2 5P1/2 F=1 795 nm light mF 2 F=2 1 0 5S1/2 -1 462 MHz -2 F=1 Hyperfine B increases

  22. Nuclear magnetic resonance

  23. NMR B-field

  24. Electron Spin Resonance (ESR) Organic salt, DPPH

  25. Microwaves

  26. Microwaves www.microwaves101.com

  27. Compton scattering: light as a particle

  28. Muon Lifetime Muons are produced in cosmic rays www.lanl.gov

  29. Muon Lifetime Properties of the Leptons www.hyperphysics.phy

  30. Muon Lifetime Decay of muon proceeds through the weak interaction

  31. Muon Lifetime Muons stopped by plastic scintillator plastic scintillator photo-multiplier tube http://alpha.sci.osaka-cu.ac.jp/grapes3

  32. Muon Lifetime Typical muon-electron pulses from the photomultiplier tube www.prestoncoll.ac.uk

  33. Plasma Plasma: “the 4th state of matter” Most common state for the visible matter in the universe. hyperphysics.phy-astr.gsu.edu

  34. Plasma Langmuir probe used to measure electron temperature Cassini approaches Saturn (Artist's impression: NASA) Langmuir probe on Cassini/Huygens (Photo: IRF Uppsala)

  35. Cavendish experiment:measure of G, gravitational constant http://fas.harvard.edu

  36. 2 equilibrium positions double the accuracy

  37. Experiment 1 order

  38. Hall effect Band-gap theory of Solids

  39. Mercury

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