Why is it that Ultraviolet light is absorbed by glass?

Question

explain further...plz..

thnx.. :)

Answer 1

Generally speaking, glass does not absorb UV energy.

Common window glass is a silica based glass with additions of soda and calcium (plus some others). UV absorption is caused by electron excitation and as a result, heavier elements are generally needed for this absorption (actually you really need more loosely bound electrons...). Since none of these elements are found in window glass, it will not absorb UV light and you'll get tan sitting behind it.

Flourescent lights produce UV energy but to prevent its transmission the silicate glass comprising the shell of a flourescent light contains Cesium Oxide which introduces more loosely bound elecrons and shifts the UV absorption edge so UV energy is not transmitted

Answer 2

Generally speaking, transparency to light becomes less as the wavelength decreases because the photon energy becomes comparable to that of the lowest energy electronic transitions in the atoms. This means interactions can occur which absorb the photons instead of transmit them. Media with stronger bonds, like quartz, sapphire, and diamond, usually have more strongly bonded electrons, so can transmit the lowest wavelengths (well into the UV).

Answer 3

It enters, but it has total internal reflection, so it doesn't escape.