The emission spectrum of a black body at two different temperatures are shown by curyes P and Q (as shown in figure). The ratio of the areasunder the two curves P and Q will be

Absolute temperatures of the black body corresponding to curve P and Q are in the inverse ratio of λm(Wein's displacement law).i.e., TPTQ = 19872980Area under curves represent the total power radiated by a body and is proportional to the fourth power of absolute temperature (Stefan's law)∴ ApAQ = (TPTQ)4= 1681