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Unformatted text preview: Physics 486 Discussion Problems Week 1 (1). In class, we derived the famous Planck distribution for the energy density of radiation emitted by a blackbody source: (a). By integrating this relationship over all frequencies, , find a relationship for the total energy density radiated by a blackbody source (Hint: Make the change of variables x=h/kT, and use the fact that ). (b). You should obtain a relationship for the total energy density of the form U(T) = aT 4 , where a is a constant. This is the Stefan-Boltzmann law of radiation * . Using known values for fundamental parameters, obtain a value for a (the radiation constant): (c). The radiation emitted from a particular star is observed to have its maximum value at a wavelength of max = 456 nm. It can be shown that max decreases with the temperature of a radiating object according to Wiens Law (see derivation in class hand-out): Estimate the total energy density of radiation from the star....
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