Question

what is black body radiation nd who gave this theory

Answer 1

Hey mate here's your answer

Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body). It has a specific spectrum and intensity that depends only on the body's temperature.

It was given by Plank.

Hope it helps you

Answer 2

Quantum theory owes it's origin to the study of thermal radiation in particular to the Black Body radiation which was first defined by Robert Kirchoff in 1859-1860