Template talk:SI radiometry units

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Physics (Rated Template-class)
WikiProject icon This template 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.
 Template  This template does not require a rating on the project's quality scale.

Older comments[edit]

Added "confusingly called intensity" to radiance as well. Per steradian is used in Allens "Astrophysical Quantities", and Chandrasekhar's "Radiative Transfer" which are classics.PAR 07:58, 16 November 2005 (UTC)

Included per frequency for spectral radiance and irradiance. I believe per wavelength is favored by experimentalists, per Hertz by theoreticians. Also, I removed "cubic meter" because even though the units are meter3 this is not a "volume". Strictly speaking the meters in the area calculation are different units that the meters of wavelength. (See H.E. Huntley, "Dimensional analysis".) PAR 18:09, 18 December 2005 (UTC)

Shouldn't they be watts-PER, not watts-TIMES?[edit]

Am I nuts, or shouldn't ALL of the entries in the abbreviation column be W/whatever (watts PER whatever), not W·whatever (watts TIMES whatever)?

If I'm nuts, my apologies... but acting on WP:BOLD I'm going to change them, and see what happens. Dpbsmith (talk) 23:39, 17 May 2006 (UTC)

Never mind, I figured it out... yeah, that's what the minus signs on the superscripts are for, right. Sorry. Dpbsmith (talk) 23:50, 17 May 2006 (UTC)

Intensity and intensity are not the same thing[edit]

Note that the article Intensity (physics) is about intensity as power per unit area. The links to the usage of this term to mean irradiance, radiant exitance, and radiant emittance are correct. The comment that radiance is sometimes called intensity should not be linked to the article Intensity (physics), because Wikipedia organizes information by concept not by name. If there were an article on intensity as power per steradian per square meter, it would be appropriate to link to that article. In the absence of that, no link is appropriate. Essentially, there are two distinct meanings of "intensity" here (and a third elsewhere in the template). While they have the same name, they are distinct things and should not be confused (which is the point of that note in the first place). The intensity article also discusses this confusion of terminology, of course.--Srleffler 15:51, 26 June 2006 (UTC)

Template SI photon units[edit]

FWIW, I created a template named Template:SI photon units in analogy to Template:SI radiometry units and SI photometry units aka Template:SI light units. It's still "raw", but perhaps useful to some. --Matthiaspaul (talk) 16:55, 17 August 2011 (UTC)

Too wordy[edit]

I disagree with this edit. It is not necessary to tell a reader of the English Wikipedia that the English word "energetic" begins with a small latin letter e, nor that the English word "visual" begins with a small latin letter v. This is unnecessarily wordy, in a place (a footnote on a template) where we should be as concise as possible. Linking to articles on letters of the alphabet in a template on optics is a clear example of overlinking.--Srleffler (talk) 23:52, 19 August 2011 (UTC)

Actually, while it might look obvious to you (and to some extent to me as well), I don't think it's unnecessary—English speaking people in another cultural context might draw quite different conclusions unless something gets spelled out verbatim. I have seen too many examples (including in WP) where the letters were mixed up. Apparently, many people don't know or don't recognize the differences, and some display fonts are of no particular help here either since they don't visually distinguish between them at all. This is causing uncertainty if not confusion, in particular if people also don't use the suffix e. Of course, the information can be lifted from dimensional analysis, but this doesn't help those who are new to this and eager to learn. In order to help get it straight, we should really be nitpickingly specific here IMO. Although the problem is less prevalent with the e than it is with the v, in some fonts the small Greek letter epsilon is rendered very similar to the glyph used for the small Latin letter e. Addressing your plea, I will nevertheless try to find a more compact form of wording.
Also, I don't like the fact, that the notes are showing below the tables. I would rather have them grouped with the other notes at the bottom of an article, where they are less obstructive, but hesitated to add any implicit usage prerequisites on the templates. At least, I would like them to not reuse the same indices already used up in the other tables (if both are embedded into an article at the same time), but don't know how to reopen an already closed group of references without resetting the index counter back to 1. Perhaps this can be automated, but I will first try it the pragmatic way and implement another parameter to control this. I hope you will find this useful as well. --Matthiaspaul (talk) 12:58, 20 August 2011 (UTC)
I agree that confusion between western and Greek letters is an issue (particularly nu and v), but telling the reader that "v" stands for "visual" is completely sufficient to solve the problem, for the photonic units. No sensible reader could think that the "v" is a nu after reading that it stands for "visual". --Srleffler (talk) 15:23, 20 August 2011 (UTC)
The footnotes have been truncated a bit and the templates now support a 3rd calling parameter. Thereby it is now possible to freely rename, move and/or combine the footnotes to elsewhere in the article, for example collect them in a single Notes section at the bottom of the article. See Photometry (optics). --Matthiaspaul (talk) 01:11, 21 August 2011 (UTC)


The table indicates that radiosity is power (presumably radiant flux) per unit area - watts / metre2. The article on radiosity indicates that it is radiant intensity per area - i.e., watts / steradian / metre2. Which is correct, or is their an ambiguity in usage? — Pingkudimmi 09:34, 10 August 2012 (UTC)

Some of the wording in the article seems to be ambiguous or incorrect. Looking at the math, the definition section appears to say that the radiosity is the radiant intensity (W/sr), integrated over solid angle, which would make the units simply watts. The "radiosity method" section refers to "intensity" but appears to mean irradiance (W/m2) rather than radiant intensity. In that section, radiosity appears to have dimensions W/m2. It looks like there is an ambiguity in usage.--Srleffler (talk) 05:43, 11 August 2012 (UTC)

Too big?[edit]

I'm not sure it was a good idea adding emissivity, absorptivity etc. to the template. This table was already much too big.--Srleffler (talk) 04:13, 7 March 2015 (UTC)

Reflectance and transmittance?[edit]

I removed reflectance and transmittance. It's not clear to me that the definitions were correct. "Radiance reflected by a system within a given solid angle, divided by radiance reflected by the system within another given solid angle." does not seem correct to me. Reflectance and transmittance are usually defined in proportion to what is incident, not to what is reflected in some other direction. This definition is either wrong or it is some specialized use of the term—too specialized to be presented in this table as a general definition. Defining these quantities in terms of radiance specifically may also not be correct. I'm more familiar with reflectance and transmittance as measures of relative irradiance, not radiance.--Srleffler (talk) 04:33, 7 March 2015 (UTC)