NATS 1945 Lecture 9: Chapter 9 & 10 review notes
29 Nov 2016
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Infrared light has a wavelength longer than visible light. Longest visible light wave is about 0. 65 microns. Everything emits light except those with an absolute 0. Infrared light can be 0. 65-20 microns long, frequency is lower temperature, because of shaking electrons creating electromagnetic waves. Things that emit glowing from heat are called thermal radiation or heat radiation. Blue flames are hotter than red flames. Hotter electrons shake faster, higher frequency (bluer) radiation, shorter wavelength. White roofs, sunlight reflected off (does not absorb heat as much). A roof that has dark paint but can reflect infrared light and absorb. This can lower ac costs, but white roofs are too bright for people"s eyes. visible light is the solution. The paint is (cid:498)white in the infrared(cid:499). flowing through the wire makes it very hot, about 2500k. Tungsten light bulbs have small tungsten wires inside. Light bulbs use much more energy than they radiate.
