ASTA02H3 Lecture Notes - Lecture 4: Black Body, Photon
Document Summary
What is a spectrum: the distribution of photon energies coming from a light source, spectra are seen by passing light through a spectrograph, we can tell how many photons are distributed based on wavelength. A hot, low-density gas, in which the atoms are relatively isolated from each other will emit an emission-line spectrum. Only emits light at particular wavelengths, giving the appearance of bright, discrete emission lines. Each element has a unique set of emission-line spectrum (it can be seen as the element"s footprint". Slightly different els for isotopes of the same element. Light from a continuous spectrum through a vessel containing a cooler gas shows a continuous spectrum from the lamp crossed by dark absorption lines at wavelengths. A hot solid or hot, dense gas produces a continuous spectrum. Plenty of collisions between the photons and the matter for the latter. An object that absorbs all light (all wavelengths) As it absorbs light, it heats up (characterized by temperature)
