826.2 The appearance of Plank's constant h c Ideal blackbody a body that absorbs all radiation incident on it is called ideal blackbody 1879 Josef Stefan found an empirical relation between the power per unit area radiated by a blackbody and the temperature RIOT 4 526.2 The appearance of Plank' s constant h Wiens displacement law .T=0.28978×10mK 4000K7 ™Ideal blackbody A body that absorbs all radiation incident on it is called ideal blackbody. 1879 Josef Stefan found an empirical relation between the power per unit area radiated by a blackbody and the temperature. 4 R = σT §26.2 The appearance of Plank’s constant h §26.2 The appearance of Plank’s constant h ™Wien’s displacement law 0.28978 10 m K 2 max = × ⋅ − λ T