Electromagnetic spectrum and visible light
The electromagnetic spectrum also covers all wavelengths of light may have, from thousands of miles to femtómetros. That's why most of the schematic representations are usually logarithmic scale.
Across the spectrum, the portion that human beings can see is very small compared to other spectral regions. This region, called the visible spectrum comprises wavelengths from 380nm up to 780nm. The light from each of these wavelengths is perceived by the human eye as a different color, so, in the breakdown of white light in all wavelengths by prisms or by rain in the rainbow, eye sees all colors. See figure 1.
The color temperature of light source is defined by comparing its color within the light spectrum with light to emit a black body heated to a given temperature. For this reason the color temperature in degrees Kelvin, while not explicitly reflect a temperature measurement, being the same only a relative measure. See figure 2.
- 1700 K: Light a match.
- 1850K: Candlelight.
- 2800 K: Incandescent or tungsten (standard household lighting.)
- 3200 K: Tungsteno (professional lighting).
- 500 K: Daylight, electronic flash (approx).
- 55770 K: Color temperature of pure sunlight.
- 6420 K: Xenon lamp.
- 9300 K: Screen TV (CRT)
- 28000 to 30000 K: Lighting