thermal_radiation_theory

thermal_radiation_theory - Comparing the experimental...

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Comparing the experimental results with the theory of thermal radiation The amount of thermal radiation energy dI emitted by a body in an interval of frequencies [ ω,ω + ] is given by the Planck’s formula: dI ( ω ) = C 1 ω 3 e ¯ hω/kT - 1 where ¯ h 6 . 6 · 10 - 34 J · s is the Planck’s constant, k 1 . 4 · 10 - 23 J/K is the Boltzmann’s constnat, and C 1 is a constant the value of which will be unimportant to us. The value of C 1 , in particular, on how close is your physical realization of a black body to an ideal black body. The function dI = C 1 ω 3 e ¯ hω/kT - 1 is called the intensity distribution of the radiation. The formula above shows that radiation is emitted at all frequencies, although in different amounts. When you measure the radiation amount with a detector, the output depends on the intensity and frequency of radiation. A detector is charac- terized by the sensitivity function F ( ω ) which tells you what output voltage dV you get if you illuminate the detector with a monochromatic radiation. The expression is
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This note was uploaded on 12/13/2011 for the course PHYS 309 taught by Professor Staff during the Spring '10 term at South Carolina.

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thermal_radiation_theory - Comparing the experimental...

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