Question

What is the difference between reflection and emissionof radiation ?

Answer 1

In reflection light from external source is coming and colliding with the reflector wall. It then interact with the charges in the new medium and direction of the light changes. Some or full part of the light goes back to the same medium, this is reflection.

In case of emission of radiation medium generally convert other form of energy to the em energy. Like we get energy by burning something. It can also absorb em energy and the reemit again. So in this case frequency of the em wave may change, but in this case wavelength may change. Like if we heat some metal we get light.

But in case of reflection wavelength generally does not change.