State Stefan-Boltzmann law.

Explanation

Stefan - Boltzmann law states that the total amount of heat radiated per second per unit area of a black body is directly proportimal to the fourth power of its absolute temperature .
`E alpha T^( 4) " or " E = sigma T^(4)`
Where `sigma ` is known as Stefan 's constant. Its value is `5 .67 xx 10^(-8) W m^(-2) k^(-4)`