Here are the answers that I have received till today, after extending the closing date by a month.
Physics Question: We have all seen shiny black objects, e.g. well-polished shoes. These objects are shiny presumably because they reflect light in a certain manner. But … black objects, by definition, are supposed to absorb all incident light.
So how are the two properties consistent?
> There are two ways in which light can be reflected from an object:
> 1) Diffuse reflection: parallel rays are reflected in random
> directions spreading out everywhere. This happens if the surface is
> 2) Specular reflection (as in a mirror): parallel rays emerge as
> parallel rays. This happens if the surface is smooth.
> Diffuse reflection gives objects their characteristic color/shade.
> Which colors in the visible range are reflected depend on the
> electronic structure of the molecules.
> Specular reflection causes objects to look shiny because the rays are
> reflected in a regular manner, and so you can observe a perfect
> reflection of, say, a light source.
> A black object can appear shiny if no color in the visible range
> undergoes diffuse reflection but some surface effect (due to the
> presence of a chemical coating along with at least partial smoothness
> due to polishing) causes some of the light to be specularly reflected.
> Essentially, you have different surface layers that contribute to
> complete diffuse absorption (black shade) and partial or complete
> specular reflection (shiny effect).