The color of the emitted light depends on the relative heights of the starting and ending energy levels. A crash between closely spaced levels (such as two and one) releases a pulse of low-energy reddish light, while a crash between more widely spaced levels (say, five and two) releases high-energy purple light.
The air around you is filled with floating atoms, sliding down the Earth's spacetime curve. Atoms first assembled in the cores of long-dead stars. Atoms within you, everywhere, disintegrating in radioactive decays. Beneath your feet, the floor - whose electrons refuse to let yours pass, thus making you able to stand and walk and run. Earth, your planet, a lump of matter made out of the three quantum fields known to mankind, held together by gravity, the so-called fourth force (even though it isn't a force), floating within and through spacetime.
Also unlike a planet, an electron—if excited by heat or light—can leap from its low-energy shell to an empty, high-energy shell. The electron cannot stay in the high-energy state for long, so it soon crashes back down. But this isn’t a simple back-and-forth motion, because as it crashes, the electron jettisons energy by emitting light.
Stray voltage/current/frequency is the most serious form of exposure. Electrocution kills very few people per year. Stray voltage/current/frequency exposure is suspected to be making people sick in the millions!
The bridge between the electron and the other elementary particles is provided by the fine structure constant, a ~ 1/137, as manifested in the factor-of-137 spacings between the classical electron radius, electron Compton radius, and Bohr orbit radius. ... An a-quantized mass-generation grid extends accurately from the electron all the way to the top quark t, and leads to a corresponding a-quantized particle lifetime grid.