NATS 1745 Lecture Notes - Lecture 14: Photon, Spectroscopy
2 Apr 2017
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Continuous energy/light present at all wavelengths object is heated to point of glowing. Bright line (the emission line spectra") only specific wavelength/colours present high temp, low density gas. Dark line (the absorption line spectra") a continuous spectrum with gaps/dark lines. A continuous source passes through a cooler gas. Wein"s law see pdf cooler objects are redder, hotter objects are bluer. Stephan (or stephan-boltzmann) law see pdf hotter objects are brighter. < examples of black body graphs at different temperatures. To understand dark line + bright line spectra: need to understand atoms. Thompson atoms made of negative charges embedded in positive charge. This is called absorption emission is the opposite: an electron in a high energy orbit drops to lower energy orbit. Energy is emitted from atom as a photon or light wave so: dark line spectra = absorption line = stars, bright line spectra = emission line = nebulae.
