Reflection

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Generic Goon
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Reflection

Postby Generic Goon » Sun Feb 24, 2008 5:52 pm UTC

Sorry if this has already been asked, but a quick search of reflection yielded no useful results.

As I understand it, a black surface is one in which light is absorbed. Photons hit a surface, are (mostly) absorbed, and our eye sees black. A white surface is when it is reflected. Photons hit a surface, are (mostly) reflected, and our eye sees white. Colors in between are when some wavelengths of light are absorbed, and some wavelengths are reflected.

What, then, is a reflective surface (i.e. a mirror)? Is it some sort of whiter than white, where even more of the light is reflected than off a white surface? That seems to be my gut reaction, but if it is true then something about the way that I understand a white surface from above is wrong.

I'm sure this has some really simple answer, but I don't have the background in light to know it yet, and I don't feel like waiting a year to take physics before I find out.

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yy2bggggs
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Re: Reflection

Postby yy2bggggs » Sun Feb 24, 2008 6:10 pm UTC

Generic Goon wrote:What, then, is a reflective surface (i.e. a mirror)? Is it some sort of whiter than white, where even more of the light is reflected than off a white surface?

The critical difference between the mirror and the white surface is that the mirrors "reflect" light (hence the name reflectance)--light bounces straight off of the mirror in a predictable direction, and still goes to your eye. A white surface just scatters the light randomly.

When light from a normal image goes to your eye, it can be imagined to be going straight into your eye. If you hold up a pane of glass in front of you between you and the image, the light from each part of the image is still going in the same direction to your eye, so you can see through the glass and see the image.

Now imagine how the light works just on the side of the glass you are on--light from each part of the image is traveling in a particular direction to your eye, and you are able to resolve the image. That's how the light from the mirror goes to your eye as well.

It's not about the amount of light here--it's about the degree of scattering.
Image

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Dropzone
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Re: Reflection

Postby Dropzone » Sun Feb 24, 2008 6:17 pm UTC

Both white and mirrored surfaces reflect light, but they reflect it in two different ways. White surfaces are those which exhibit diffuse reflection, i.e. the reflected light is scattered in random directions. Mirrored surfaces are those which exhibit specular reflection, which means that the reflected light travels in a consistent and predictable manner (the angle of reflection equals the angle of incidence). The fact that diffusely reflected light is randomly scattered means that it never forms a recognisable image, unlike specularly reflected light.

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TomBot
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Re: Reflection

Postby TomBot » Sun Feb 24, 2008 7:50 pm UTC

Think of a mirror floating in space. Most of the time, except for stars, it would look black. But if it was at just the right angle, it would appear blindingly white as it reflects the sun.

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evilbeanfiend
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Re: Reflection

Postby evilbeanfiend » Mon Feb 25, 2008 11:16 am UTC

TomBot wrote:Think of a mirror floating in space. Most of the time, except for stars, it would look black. But if it was at just the right angle, it would appear blindingly white as it reflects the sun.


conversely a white sheet floating in space would look white from many different angles
in ur beanz makin u eveel


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