1.A perfect black body is one which

2.40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is

3.Depending on the radiating properties, a body will be black when

4.Planck's law holds good for

5.The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit