How is black-body radiation generated?

Answer 1

Accounting for black body radiation was one of the main things that led to quantum theory. A black body is a perfect absorber of radiation and so, conversely, it must be a perfect emitter of radiation. The radiation it emits depends on its temperature, and the source of the radiation is thermal excitation of electron orbitals.

Classical considerations led to the prediction that the amount of black body radiation would increase with frequency - so infinite amounts of energy would be being emitted at the ultra violet end of the spectrum (the so called ultra violet catastrophe).

Plank resolved this by assuming that atoms could only radiate at energies that were discrete, integer multiples of a fundamental unit of energy (hence he invented the concept of quantisation) rather than continuously as in classical physics.

Answer 2

epidavros is correct, but an answer can be stated more simply.

Warm or hot bodies are hot because the atoms are vibrating with thermal energy. The hotter they are, the more vibration energy an atom has, on average. Some of the vibration energy is transferred to the electrons which radiate.

All warm bodies radiate; some more than others given equal temperatures. Black bodies radiate the most. So scientists have focused on black bodies because it is a specific, well defined case, that can be produced in the laboratory with good accuracy.

The exact quantitative details of the radiation cannot be explained with classical physics, and required advancements in quantum mechanics for a full explanation.

Answer 3

A white physique reflects all electromagnetic radiation and a black physique absorbs all electromagnetic radiation (interior of that area of the easy spectrum of interest). easy photons work together with the electrons orbiting atoms and molecules and are released as comparable or diverse photons. Black bodies emit purely infrared (below purple on the spectrum) which we experience as warmth fairly than seen easy.

Answer 4

Sorry Just "JR", this is not correct. A black boddy is something that does not reflect light. It does emit radiation.

Answer 5

By definition, a black body does NOT emit any radiation!
(If it did, it would not be "totally" black...)