The flow of electrons through the gases excites the electrons in the mercury atoms, which then emit ultraviolet (UV) radiation. Primary light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic radiation, and include light bulbs and stars like the Sun., cat eyes, retroreflectors) do not actually. emission of light Modern theory explains the emission of light by matter in terms of electronic energy levels. That materials, when heated in flames or put. Fluorescence occurs when an electron in an atomic orbital absorbs energy from some source (like an interaction with a photon, or a collision with another atom) is promoted to a higher energy level and then, on 'falling back', releases some of that energy in the form of visible light. An object that emits light is called a lamp or an illuminant, though we avoid the latter terminology since we generally use “illuminant” to refer to a spectral distribution of emission. In a fluorescent lamp, the emitted light is in the visible spectrum -- the phosphor gives off white light we can see. Conventional incandescent light bulbs also emit a good bit of ultraviolet light, but they. A lamp is basically any device that converts energy (usually electrical) into visible light.
