Why the white light is transmitted by a common glass without undergoing any alteration?
Beacause of that we can see the light coming from objects, no matter if a glass is between the object and us. It’s different when a translucent glass is placed in the middle: we can not see a clear image (kind of blurred image) of the object.
SpeedDemon
on February 8th, 2012
It’s not totally unaltered:
The most obvious characteristic of ordinary glass is that it is transparent to visible light (not all glassy materials are). This transparency is due to an absence of electronic transition states in the range of visible light, and because ordinary glass is homogeneous on all length scales greater than about a wavelength of visible light. (Heterogeneities cause light to be scattered, breaking up any coherent image transmission). Ordinary glass partially blocks UVA (wavelength between 400 and 300 nm) and totally blocks UVC and UVB (wavelengths shorter than 300 nm) due to the addition of compounds such as soda ash (sodium carbonate).
Gilbert
on February 8th, 2012
it is altered. There is some reflection (like when you can see your reflection in a store window) and there is some refraction (like a bent pencil in a glass of water only less so).
FeralFeline
on February 8th, 2012
The answer to this depends on the angle. If you are talking about something directly in front of you, it has to do with interference. Light will reflect off the front and back surface of the glass. If the glass thickness is at the right amount, you can get total destruction of the waves and not see through the glass at all. The fact that the incident rays are perpendicular to the surface means that there is no refraction and so the waves will not disperse. But if you make a prism out of glass, the light gets distorted to the point that it breaks up into the rainbow spectrum since the frequencies are traveling at different phase velocities (this is called dispersion).