f10_sep21 - Ast 307 Tues Sep 21 Light Spectra Wavelength...

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Ast 307 - Tues., Sep. 21: Light & Spectra Light as Wave and Particle Thermal (blackbody) Radiation Line Spectra & Kirchhoff’s Laws Wavelength, Frequency, & Energy ! " ! = c ! = wavelength = frequency c = 3.00 x 10 8 m/s = speed of light E = h " = photon energy h = 6.626 x 10 -34 Joule s = photon energy 1 electron volt = 1 eV = 1.60 x 10 -19 Joule Light as Particles Light can be treated as photons – packets of energy. The energy carried by each photon depends on its frequency (color) E = h " = (h c)/ ! [“h” is called Planck’s Constant] Bluer light carries more energy per photon.
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The Electromagnetic Spectrum Thermal (“Blackbody”) Radiation Thermal radiation is an example (one form) of continuous spectrum (smooth variation over wavelength range; no gaps or bright spots). Nearly all large or dense (opaque) objects emit thermal radiation, including stars, planets, you… An object’s thermal radiation spectrum depends on only one property: its temperature.
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This note was uploaded on 04/30/2011 for the course AST 317 taught by Professor Dinerstein during the Fall '10 term at University of Texas.

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f10_sep21 - Ast 307 Tues Sep 21 Light Spectra Wavelength...

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