किरचॉफ के विकिरण के नियम का प्रायोगिक सत्यापन किसके द्वारा किया गया था?

For an opaque body, the relation between absorptivity α, reflectivity ρ, and transmissivity τ is:

The physical law stating that the total energy emitted per unit surface area of a black body is directly proportional to the fourth power of its absolute temperature is: