AST201H5 Lecture 9: AST Lecture 9
Document Summary
Kirchhoff"s laws of radiation: a hot solid or liquid or dense gas. Type of heated material does not affect the radiation, all produce same continuous spectrum. Two laws of thermal radiation: stefan-boltzmann law - total amount of radiation (summed over all wavelengths) increases rapidly with increasing temperature. Total radiation varies as t^4 (kelvin: wien"s law - as the temp increases, the wavelength where the emission is greatest becomes smaller. Wien"s law is easier to use than stefan boltzmann, because we just need the peak emission. Temp = 2900000 k nm/470nm = 6170 k. A thin, heated gas emits radiation at only certain wavelengths. There is no radiation at wavelength between these emissions emission line-spectrum. Changing the temp of the gas has almost no effect on the spectral pattern.
