The visible spectrum in terms of electromagnetic waves and their wavelengths:


The shorter the wave, the more energy.


Longer than red is infrared, which can cause you to feel warm, this starts at 3 um or so.


Past violet is the dangerous ranges. Ultraviolet, beginning at  100nm, can cause cancer. X-Rays (otherwise known by their older name of Rontgen Rays) can cause cell damage, as can Gamma Rays which are emitted by radiactive substances and are the most penetrative of radiation. X- Rays begin at  5nm and Gamma at about 0.01nm.


Microwaves are actually longer than light and start at about 3cm. They excite water molecules in the body, and the shorter they get the more effect. at 1380 nm this can cause a serious heating effect which leaves you feeling cooked as the molecules absorb all the energy.


Wavelength (l) frequency (f) conversions:


c = f l      f = c / l      l = c/f



c is the speed of light in a vacuum,   300, 000, 000 m/s  or  3 X 10