ASTR 1210 Lecture Notes - Lecture 10: Photon Energy, Emission Spectrum, Photon
24 Oct 2016
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Today: matter (cont. , recap, inferring properties of matter from light, inferring motions of objects from light. Electrons in an atom are held in orbit around nucleus by electrical force: kind of like a planet around a sun. Can occupy many discrete orbits: each orbit is an energy level (like the rungs on a latter specific heights) What is the structure of matter: matter is made of atoms, which consist of a nucleus of protons and neutrons surrounded by a cloud of electrons. How is energy stored in atoms: the energies of electrons in atoms correspond to discrete energy levels. Spectra: most astronomical information comes from spectra of light. Spectrum = distribution of light intensity at different wavelengths: a graph of intensity vs. wavelength. Continuous spectrum (light bulb: kirchhoff"s first law spans all visible wavelengths without interruption. Emission spectrum (neon lamp: thin/low-density cloud of hot gas emits light only at specific wavelengths producing a spectrum with bright emission lines.
