Why is there different radiation for object?

Question

We know that all objects emit radiation at different wavelengths.

I am talking about normal objects(not black body).

I would appreciate the explanation how for example a table can emit radiation at different multiple wavelengths at the same time ? I thought it just emitted radiation lets say at x wavelength but turns out there are multiple wavelengths(hence multiple spectra). Note that I am looking for an explanation at an atomic level

I get that electrons move at higher orbital and when they get back to ground, they release energy and emit radiation, but what I am asking is at the specific time(lets call this ‘t’), would there be multiple wavelength radiation or only specific one ?

A good example could be a person that emits infrared and visible radiation at the same time. How ? Some atoms have higher energy and they produce visible radiation while other atoms in a person have less energy hence those emit infrared ?

Answer 1

I am talking about normal objects(not black body).

Can I ask why you make the distinction? Many normal objects behave similarly to black bodies in this particular case.

I get that electrons move at higher orbital and when they get back to ground, they release energy and emit radiation

For discrete atoms and small molecules, this is very significant. The limited arrangement of orbitals means that only certain wavelengths are easily absorbed or emitted.

But for solid materials, the complex relationship of the molecules and the bonds between them allows many, many more possible energy levels. While an oxygen atom might be in a ground state, a chair cannot be. The "choice" of what wavelength to emit is probabilistic depending on the amount of energy available.

Humans do not emit visible radiation unless they are on fire or something similar. The reflection of visible light is a different mechanism. But yes, it is a question of energy. The more concentrated the energy, the more emission can happen at shorter wavelengths.