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Oh, Be A Funny Geek, Kiss Me
"Two things fill my mind with ever increasing wonder and awe the more
often and the more intensely the reflection dwells on them: the starry
heavens above and the moral comprehension within me"
Carved on the gravestone of Emanual Kant,
the 18th century philosopher.
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Read Chapter 23, chap 4.6-4.10. HW#1 Due Tommorow. HW#2 is now available. |
First 10 minutes quiz: end of class on Friday. 1st question: What's
your seat #.
Look it up by clicking here! Observations:
Remember to check message, bring warm closthes. (See the blue members here...) Reminder: The Doppler effect formula (also in lab #1) is:
Regarding what to learn for the exam and what to read: Since the notes do not follow the textbook religiously: a. Regarding reading assignments: The minimum requirements are on the web page. The best results will be achieved by also reading the chapters in the syllabus. b. There will be a help session on February 14 at 7:00pm in this room
(hopefully). The exam coverage will be outlined in that session, and on
the web.
1. "Black Body" radiation: Kirchoff laws: absorption lines, emission lines, "rainbows". On BB: Emission lines bar-code & intensity graph, absorption lines bar-code & intensity graph. Further discussion of "rainbows": Max. of intensity: Wien's Displacement law: Temperature = 289.8 x 10 4 nm Kelvin/ lmax. 0 Kelvin = - 273.15 Celsius. Light with changing intensity demo: what happens to the spectrum? Hard to see because our eyes evolved to see in the visible! (redder - colder) "Barcode" on Black Body (Rainbow spectra). Why do we have different spectra for different stars? Spectrum is a result of Black Body emission partly absorbed by atomic transitions in atoms in the way (as in Kirchoff rules from Jan 31). Ionization of hydrogen (& other) atoms due to high temp in their outer layers prevents these atoms from absorbing the Black Body (rainbow) spectrum. Colder atoms: Photons excite more levels. Can be absorbed more easily. Scheme of determining the stellar type: O0-9, B0-9, A0-9, F0-9, G0-9,
K0-9, M0-9.
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