When an atom emits light, it undergoes a process called "emission of photons." This typically occurs when an atom transitions from a higher energy state to a lower energy state. There are different stages to this process:
1. Excitation:
The atom absorbs energy, often in the form of heat or light. This energy excites the electrons in the atom, causing them to move to higher energy levels or orbits.
2. Relaxation:
The excited electrons are not stable in these higher energy levels and tend to return to their original, lower energy levels. As they do so, they release the excess energy they gain in the form of photons.
3. Photon Emission:
Each electron transition corresponds to the emission of a photon. The energy of the photon is directly related to the energy difference between the higher and lower energy states. The wavelength (and colour) of the emitted light is determined by the energy of the photon.