Compare two blackbody objects,one at 200 K and one at 400 K.How much larger is the flux from the 400 K object,compared to the flux from the 200 K object?
A) Twice as much
B) Four times as much
C) Eight times as much
D) Sixteen times as much

Question

Quizplus · Accepted Answer

The flux of a blackbody is proportional to the fourth power of its temperature (Stefan-Boltzmann law). Therefore, the ratio of fluxes between two blackbodies at temperatures T1 and T2 is (T2/T1)^4. In this case, we have T1 = 200 K and T2 = 400 K, so the ratio of fluxes is (400/200)^4 = 16. Therefore, the flux from the 400 K object is 16 times larger than the flux from the 200 K object.

Compare Two Blackbody Objects,one at 200 K and One at 400