Chapter 11 Fundamentals of Thermal Radiation 11-44 The variation of emissivity of a tungsten filament with wavelength is given. The average emissivity, absorptivity, and reflectivity of the filament are to be determined for two temperatures. Analysis(a) T= 2000 K 066728.0fmK2000=K)m)(20001(11=⎯→⎯=λμμλTThe average emissivity of this surface is ελλ, μm1 0.5 0.150.173=−+=−+=)066728.01)(15.0()066728.0)(5.0()1()(1121εffTFrom Kirchhoff’s law, α==0.173(at 2000 K) and
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.