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Name:  Michiru K.
Status: student
Age: 18
Location: N/A
Country: N/A
Date: 2000-2001


Question:
Leaves appear green in colour because they reflect green colour while absorbing others. Black absorbs all the wavelengths in the visible spectrum while white reflects all of it. My questions are:

1) What wavelengths does silver colour reflects/absorbs?
2) Why is glass transparent?


Replies:
Answer to question 2 - why is glass transparent ?

The reason why metal reflects light lies upon the fact that the bonding between atoms of metal are made up of free electrons. Free electrons cause the light to be reflected and the surface of a metal like silver happens to be brilliant. On the other hand, the atomic bonds between Silicon, Oxygen, Calcium, Sodium, Lead, Bhorium, etc, are predominantly covalent which in return allows the light to travel through it. Without the presence of free electrons the light finds ist way through the glass crystal. And - furthermore - can sometimes find it in two or three directions ( like for instance in calcite : CaCO3 with two directions ). Because of the interference between the electromagnetic nature of the light and that of the transparent crystal, the light travels through it with slower speed (in one, two or more directions).

Answer to question 1 - what wavelength does silver colour reflect/absorb ?

Based upon the arguments used on the answer nr. 1, the silver colour reflects almost all the wavelenghts that strike on its surface, whatever its origin !!!. Including radiant energy of fire ( observe the silver coating cloth of men that fight against fire ). Likewise the brilliant internal surface of the thermalflask avoid scaping of radiant energy.

Alcir Grohmann


Mirrors (silvered surfaces) reflect almost all incident light by specular reflection, i.e. no scattering so that the angle of incidence equals the angle of reflection. This distinguishes it from a white surface that reflects almost all incident light but at various angles of reflection.

Glass is transparent because it reflects very little of the incident light. It bends the incident ray of light, but reflects very little of it.

Vince Calder



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