the sun is the astronomical body that emits light in the visible spectrum.
the sun is the astronomical body that emits light in the visible spectrum.
which astronomical bodies emit light in the visible spectrum?
the sun
Na
Na
the tagging pattern can also be varied to enable sorting of mail according to the service class.









































section::::methods and detection.









































section::::methods and detection.:fluorescence.









































upon absorption of light, fluorescent materials emit light upon of a longer wavelength (lower energy) than the absorbed radiation, but cease to do so once immediately, when the illumination is stopped. the tagging of stamps uses substances that absorb ultraviolet light of wavelengths between 300 nm and 450 nm ("black light", uva, long-wave uv) and emit light in the visible spectrum. under uv illumination they usually glow a greenish or yellowish colour.
tagging (stamp)