# Talk:Reflectivity

WikiProject Physics (Rated Start-class, Mid-importance)
This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start  This article has been rated as Start-Class on the project's quality scale.
Mid  This article has been rated as Mid-importance on the project's importance scale.

## IN RESPONSE TO REAL WORLD DATA

I agree. Incidentally, the reference at the following link is surprisingly the only one I found that put experimental points on the Fresnel equations on a FLAT water surface! http://journals.ametsoc.org/doi/pdf/10.1175/2007JTECHA1049.1

I think it could be cited at the end of the sentence "That part of incident light that is reflected from a body of water is specular and is calculated by the Fresnel equations." Yet, the sentence should be changed to : "The specular portion of incident light reflected from a body of water is calculated by the Fresnel equations." —Preceding unsigned comment added by 68.193.231.122 (talk) 05:09, 21 April 2011 (UTC)

## water reflectance

Should the following be added? If so, where?

That part of incident light that is reflected from a body of water is specular and is calculated by the Fresnel equations. Fresnel reflection is directional and therefore does not contribute significantly to albedo which is primarily diffuse reflection. A graph showing the reflectivity of water vs. incident angle of can be seen at[1].

A real water surface may be wavy. Reflectance assuming a flat surface as given by the Fresnel equations can be adjusted to account for waviness. A formula and graph for correction for waviness for two different wave energy spectrum definitions exists. [1] 4.232.0.81 02:39, 11 August 2006 (UTC)

## Reflectance

This is currently the Reflectivity and Reflectance article -- it should say so right at the top.-69.87.202.60 11:49, 17 May 2007 (UTC)

I am inclined to delete this entire section and replace it with a more accurate definition of reflectance, unless somebody can provide a reference for where this definition of reflectance originates. Bulk reflectivity is not called reflectance any more than thin film reflectance is called reflectivity. They are two fundamentally different, albeit related quantities. In any case, I will provide the proper optical/physical definition of reflectivity and reflectance. —Preceding unsigned comment added by Nanoguitar (talkcontribs) 20:17, 28 May 2008 (UTC)

## metal mirrors

Reflectance vs. wavelength curves for aluminium (Al), silver (Ag), and gold (Au) metal mirrors

This is a nice graph; might be nice to also have it in the mirror article. It would be of more general use if the bounds of visible light could be added.-69.87.202.60 11:52, 17 May 2007 (UTC)

## data needed

Please add typical range of total visible-light reflectivity for ordinary mirrors (80%?), white paper (up to at least 90%?), other ordinary white surfaces, and ordinary black surfaces. And spectral curves for all of those, too, from UV to IR, with the visible portion clearly marked.

And, links to great sources of such details.-69.87.202.60 11:59, 17 May 2007 (UTC)

## Human eye

This seems to be the pure physics term/concept. In dealing with light, much of the terminology is weighted by the response of the human eye to different colors (Lumens, for example). What is the term for reflectance, weighted in the visible spectrum by the human visual response? It should be at least mentioned in this article, and linked to.-69.87.204.232 11:26, 19 May 2007 (UTC)

Photopic spectral responsivity (cf. Color vision#Physiology of color perception) --Adoniscik (talk) 00:19, 7 February 2008 (UTC)

## Reflectance Table

• Colors
70-80% White
70-80% Light cream
55-65% Light yellow
45-50% Light green
45-50% Pink
40-45% Sky-blue
40-45% Light grey
25-35% Beige
25-35% Yellow ocher
25-35% Light brown
25-35% Olive green
20-25% Orange
20-25% Vermilion red
20-25% Medium grey
10-15% Dark green
10-15% Dark blue
10-15% Dark red
10-15% Dark grey
• Materials
95% Mirror
80% Plaster
65-75% White enamel
60-75% Glazed white tiles
60% Maple
60% Birch
40% Light oak
15-20% Dark oak
15-20% Dark walnut
15-40% Concrete
5-25% Red brick
2-10% Carbon-black
6-8% Clear glass
• Lighting design
60-90% Ideal Ceilings
35-60% Ideal Walls
30-50% Ideal Countertops

-69.87.203.133 01:04, 25 May 2007 (UTC)

Link (1) is broken. 128.12.103.70 (talk) 15:45, 14 December 2007 (UTC)

## Reflectivity units

I think the unit(s) of reflectivity must be mentioned. --Sylvestersteele (talk) 12:02, 10 February 2008 (UTC)

Reflectivity is unitless. Stonemason89 (talk) 02:21, 10 March 2010 (UTC)

## shiniest metal

i think i read somewhere that it's silver

but i think some other guys said it's rhodium

reflectivity is a function of frequency, we get that part

but if you have some standard light source, say sunlight at some place, then it's just a number —Preceding unsigned comment added by 65.107.1.165 (talk) 20:57, 24 November 2009 (UTC)

Rhodium is not particularly shiny. Silver is the shiniest metal when averaged across the entire visible spectrum, but it is exceeded in some parts of the spectrum by tin and aluminum. Stonemason89 (talk) 17:01, 6 March 2010 (UTC)

## Reflectivity vs reflectance

I'm not convinced that the distinction made in this article between "reflectivity" and "reflectance" is universal. I don't doubt that some authors define the terms that way, but unless all do the article should be less strongly worded. --Srleffler (talk) 03:24, 29 April 2010 (UTC)

## Absorptance/absorptivity/albedo

This page is redirected from "absorptance", but doesn't mention it. It does say "see also absorptivity", but the absorptivity page just says absorptivity means absorptance, which redirects here. This page should at the very least give a definition of absorptance/absorptivity, and discuss how it relates to reflectivity. Either that or there should be a separate page.

Additionally, if anyone has a good idea of how the concepts of absorptance, reflectance and emissivity relate to the concept of albedo, it would be very helpful to update this page with some details.

125.7.18.1 (talk) 01:28, 22 September 2011 (UTC)

1. ^ V. I. Haltrin, W. E. McBride III, and R. A. Arnone (2001). "SPECTRAL APPROACH TO CALCULATE SPECULAR REFLECTION OF LIGHT FROM WAVY WATER SURFACE". Proceedings of D. S. Rozhdestvensky Optical Society. pp. 133 to 138. Check date values in: `|date=` (help)