2

A White object reflects all the visible colored light but so does a flat silver object (mirror) so what makes them look so different?

This has been answered here but that shouldn't be true because white objects can be highly polished too. Also if we make a silver object irregular/rough it doesn't turn white

EDIT:

enter image description here enter image description here

(1st img) The metal surface doesn't particularly look white (as the answer claims in the above link). (2nd img) The white surface does reflects impressions of windows here but it look nothing like a mirror (in terms of showing the natural vibrant colors of the object in front of it as a mirror does). Why the difference in nature if they do almost the same thing (i.e. reflect all the colored light. Or are we missing something?

44yu5h
  • 123
  • 7

2 Answers2

2

The answer in your link is correct. But you are too.

The mirror like reflection is called specular. There are degrees of smoothness. A smoother surface will have a larger specular component to its reflection. You can see this if you polish a metal surface with finer and finer grits of sandpaper. You get a mirror with 600 grit.

The two white tiles above are both smooth, but one is smoother.

A metal surface often turn grey. This is because it absorbs some of the light, more or less equally at all wavelengths. The specular reflection keeps the color of the incoming light but is dimmer. The non-specular reflection is also dimmer. If you dim a white light, it looks grey and then fades to black.

So why don't both components look grey. They would under the right circumstances. The specular component is brighter than the non-specular component, and so looks whiter. A lot of color perception happens in your eye and can work in unexpected ways. See What is Gray, from a physics POV?.

Some metals, such as copper and gold, do not absorb uniformly across the visible spectrum. They make excellent mirrors at longer wavelengths. But they do color the reflected light by absorbing shorter wavelengths.

mmesser314
  • 49,702
1

The metallic surface is an electrical conductor while the white surface is a dielectric. These reflect light differently because a dipole response is induced in the dielectric. There's a lot more to be said about the physics, but that should be enough information to get you started down the rabbit hole.

As a sidenote, 3M does produce a dielectric material that reflects light like a mirror and with extremely high efficiency. However, it accomplishes this by structuring the dielectric in very precise, thin layers to achieve an effect that would not be possible using a bulk isotropic dielectric.

Charles
  • 11