Question

State 

1. Kirchhoff’s law of radiation, 

2. State Stefan’s law of radiation

Answer 1

1. Kirchhoff’s law: At a given temperature, the ratio of the emissive power to the absorptive power is a constant for all bodies and is equal to the emissive power of a perfect black body. 

2. Stefan’s law: The total radiation emitted by a perfectly black body per second per unit area is directly proportional to the 4th power of its absolute temperature.