Introduction to the experiments of Physics 407

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Introduction to the experiments of Physics 407
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Franck-Hertz experiment confirmation of
quantized atomic energy levels
Franck-Hertz
1st evidence Spectrum from a low-pressure
mercury lamp
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Sketch of Franck-Hertz Apparatus
Franck-Hertz
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
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Voltage between peaks corresponds to excitation
energy
Franck-Hertz
4.9 V
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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
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Hall effect in semiconductors
Hall effect
Dominated by positive carriers.
Dominated by negative carriers.
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Johnson Noise
Johnson noise
? 0 Vrms??

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Johnson Noiseway to measure Boltzmanns constant
Johnson noise
JB Johnson, Physical Review 32 (1928) 97
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Brownian motionmore evidence for thermal motion
Brownian motion
Perrins Atoms
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State space of a dynamical system
Chaos
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.
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Chaos
Chaos
10,000 red dots
Chaotic behavior is characterized by divergence
of nearby trajectories. Lyapunov exponent is a
measure of this divergence.
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Two-slit interference one photon at a
timegrappling with wave/particle duality
2 slit interference, one photon
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/
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2 slit interference, one photon
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The Faraday effect
Faraday effect
?
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Right and left circularly polarized light have
different indexes of refractions
Faraday effect
http//www.ifm.liu.se/ulfek/viz/
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Verde constant depends on wavelength
Faraday effect
Jain, Am. J. Phys. 67, August 1999, 714
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The Zeeman effect
Zeeman effect
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The Zeeman effect Mercury energy levels
Zeeman effect
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Fabry-Perot distinguishes wavelengths
Zeeman effect
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Optical Pumping
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Optical pumping
F2
5P1/2
F1
795 nm
light
mF
2
F2
1
0
5S1/2
-1
462 MHz
-2
F1
Hyperfine
B increases
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Nuclear magnetic resonance
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NMR
B-field
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Electron Spin Resonance (ESR)
Organic salt, DPPH
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Microwaves
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Microwaves
www.microwaves101.com
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Compton scattering light as a particle
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Muons are produced in cosmic rays
Muon Lifetime
www.lanl.gov
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Muon Lifetime
Properties of the Leptons
Particle Symbol Anti-particle Rest massMeV/c2 L(e) L(muon) L(tau) Lifetime(seconds)
Electron e- e 0.511 1 0 0 Stable
Neutrino(Electron) ?e ?e 0(lt7 x 10-6) 1 0 0 Stable
Muon µ- µ 105.7 0 1 0 2.20x10-6
Neutrino(Muon) ?µ ?µ 0(lt0.27) 0 1 0 Stable
Tau t- t 1777 0 0 1 2.96x10-13
Neutrino(Tau) ?t ?t 0(lt31) 0 0 1 Stable

www.hyperphysics.phy
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Decay of muon proceeds through the weak
interaction
Muon Lifetime
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Muon Lifetime
Muons stopped by plastic scintillator
plastic scintillator
photo-multiplier tube
http//alpha.sci.osaka-cu.ac.jp/grapes3
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Typical muon-electron pulses from the
photomultiplier tube
Muon Lifetime
www.prestoncoll.ac.uk
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Plasma the 4th state of matter
Plasma
Most common state for the visible matter in the
universe.
hyperphysics.phy-astr.gsu.edu
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Langmuir probe used to measure electron
temperature
Plasma
Cassini approaches Saturn (Artist's impression
NASA)
Langmuir probe on Cassini/Huygens (Photo IRF
Uppsala)
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Cavendish experimentmeasure of G, gravitational
constant
http//fas.harvard.edu
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2 equilibrium positions double the accuracy
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Experiment 1 order
1230 Douglass, Scott
1245 Marcu, Diana M.
100 Kolansky, Jeremy
115 Moberley, Andrew K.
130 Toulouse, Michael W.
145 Guthrie, Daniel F.
215 Mills, Ashleigh M.
230 Crump, Nicholas A.
245 Price, Dennis M.
300 Cao, Vincent M.
315 LePire, Steven D. 330 Simingalam, Sina












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Band-gap theory of Solids
Hall effect
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Mercury
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