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Modern physics
Physics of Astronomy, winter week 9
• Star Date
• Astrophysics Ch.5: Interaction of light &
matter
• Cyclotron frequency, Zeeman splitting
• Bohr atom, quantum numbers
• Minilectures
• Portfolio/eval preparation
http://192.211.16.13/curricular/physys2002/evals.htm
http://192.211.16.13/curricular/astro2003/astroEval.htm
Astro. Ch.5: Interaction of light & matter
History of Light quantization:
• Stefan-Boltzmann blackbody had UV catastrophe
• Planck quantized light, and solved blackbody problem
• Einstein used Planck’s quanta to explain photoelectric effect
• Compton effect demonstrated quantization of light
hc/ = Kmax + F
 
h
1  cos 
me c
Astro. Ch.5: Interaction of light & matter
History of atomic models:
• Thomson discovered electron, invented plum-pudding model
• Rutherford observed nuclear scattering, invented orbital atom
• Bohr used deBroglie’s matter waves, quantized angular
momentum, for better H atom model. En = E/n2
• Bohr model explained observed H spectra, derived
phenomenological Rydberg constant
• Quantum numbers n, l, ml (Zeeman effect)
• Solution to Schrodinger equation showed that En = E/l(l+1)
• Pauli proposed spin (ms=1/2), and Dirac derived it
Improved Bohr model
Solution to Schrodinger equation showed that En = E/l(l+1),
Where l = orbital angular momentum quantum number (l<n).
Almost the same energy for l=n-1, and for high n.
Spinning particles shift energies in B fields
Cyclotron frequency: An electron moving with speed v
perpendicular to an external magnetic field feels a Lorentz
force:
F=ma
(solve for w=v/r)
Compare to Zeeman effect. See HW hints for CO Ch.5
week 9: Monday Minilectures
Astrophysics Ch.5: Interaction of Light and Matter
Team 1: Problem 5.4, photoelectric effect, Chelsea + Brian
Team 2: Problem 5.9, electrical vs gravitational forces, Erin &
Mary
Team 3: Problem 5.14, white dwarf and uncertainty principle,
Jared + Joey (This is a really easy problem. Feel free to add
another if you like.)
Team 4: Problem 5.17, Zeeman effect, Jenny + Tristen
HW due Mon.8.March includes Giancoli problems we did in
class last Thus.26.Feb. Do you want to turn these in earlier?
Giancoli Ch.39 # 7,9; Ch.40 # 45, 46
Carroll + Ostlie Ch.5 # 4, 9, 14, 16, 17
week 9: Thursday Minilectures
Boas: Partial differentiation and series. Tuesday: Overview
and series: Zita, Ch.1. Problems Sec.15 p. 39 # 28, 29
Thursday: Boas Ch.4, PD: Do at least one of your problems
in class. HW due Tues.9.March.
Zita: overview lecture, Sec.1
Team 1: Sec.3, total differentials, Example p.151
Team 2: Sec.4, approximations, Prob.7(p.156), 13-8 (p.198)
Team 3: Sec.5, Chain rule, Prob 1, 3, 6 (p.158)
Team 4: Sec.6, Implicit differentiation, Prob.5, 6 (p.160)
Team 5: Sec.8, Max/min, Prob.11 (p.171)
4.8 Prob.1 (Zita)