one week left for my board exams.... soPLEASE ANSWERIn kirchoff's law of heat radiations it has been said that the ratio of spectral emissive power to the spectral absorptive power ( both corresp. to a wavelength )at same temperature is same for all bodies and is equal to the spectral emissive power of a black body corresp. to same wavelength at that temperature.e/ a= EThis proves that emissive power absorptive power (at same temp.)But while citing examples, books tell us the example of sodium vapour which when absorbs the light of same wavelength ( when light form some source at higher temperature is allowed to pass through it when cold ) as it would have emitted when excited.and many more examples where the temp. of absorption is not equal to that of emission... WHYTHIS CONDITION STATED IN THE LAW IS NOT OBEYED???OR AM I WRONG IN UNDERSTANDING THE LAW ???

Radhika Batra , 10 Years ago

Grade 11